History of Islamic Calligraphy in the Ottoman Empire Era

: The history of Islamic civilization during the Ottoman Empire (1299-1922 AD) is important to study because the Ottoman Empire was the largest Islamic Daulah and ruled for a long time throughout history. The purpose of this writing is to understand three main aspects: firstly, to comprehend the development of calligraphy art during the Ottoman Empire era; secondly, to explore the factors contributing to the advancement of calligraphy art; and thirdly, to analyze the implications of this progress. The research method employed in this study is the historical method. The sources used in this research consist of books and journals related to the history of the Ottoman Empire. This writing resulted in three things. First, the form of Ottoman Empire calligraphy in the form of Al-Qur'an writing, ornaments on religious buildings, and the establishment of a calligraphy school. Second, the factors for the advancement of calligraphy are religious enthusiasm, support from leaders, and love for calligraphy. Third, the implications of the art of calligraphy are the emergence of a new style of calligraphy, Istanbul being the center of Islamic calligraphy, and calligraphy can be used as a medium for learning mathematics. The research is expected to contribute to the implementation of the art of calligraphy as a worldly reflection on the word and to contribute thoughts to the development of


Introduction
History etymologically comes from the Arabic syajarah which means tree.In English history is called history which means human activity related to certain events that are arranged chronologically.In historical terminology, it means records related to various past events that are enshrined in writing and have a wide scope, and are loaded with important experiences that concern the development of the state of society (Nasution, 2013;Zubaidah, 2016).While the Islamic civilization in Arabic is called al-Hadharah al-Islamiyah.Civilization is etymologically derived from the Arabic word "adab" meaning high value.In terms of civilization, it means inner progress that concerns the manners, language, and culture of a nation.While the word Islam itself refers to the religion of Islam.So it can be concluded that the history of Islamic civilization is a description of the life of past Muslims who have progressed as a result of their creation, taste, and feelings in various aspects of life towards an advance that elevates their dignity and dignity (Pulungan, 2017;Sari, 2015;Sewang, 2017).
The history of Islamic civilization is important to study, especially during the Ottoman Empire.This is corroborated by three reasons: First, historically the Ottoman Empire was the largest and long-reigning Islamic Daulah in history and contributed greatly to the development of Islam in the Asian, African, and European regions (Asra et al., 2018;Putri et al., s2021).Secondly, geographically Turkey is a country located on two continents.Its area is located on the Asian continent with an area of 790,200 km2 and the European continent with an area of 24,378 km2 so the total area is 814,578 km2.This strategic position is what makes Turkey a bridge between Eastern and Western nations (Uliyah, 2021).Third, sociologically, the Ottoman Empire society has heterogeneous characteristics which consist of various ethnic groups and religions with the nature of a society that always wants to advance and a simple lifestyle (F.Rahman, 2018).They are a dynamic nation, broad-minded, and have a high fighting spirit.
The development and government of Islam in Turkey cannot be separated from the role of the Ottoman dynasty.The Ottoman Empire was one of the three major empires that emerged after the collapse of the Abbasid Daulah.For Europeans, the Ottoman Empire was a very frightening scourge, but for Islam, it was very instrumental in the development and civilization of Islam (Djalil, 2017).The Ottoman Empire was the longest-running Islamic empire.The Ottoman Turks had succeeded in expanding their territory to three continents, namely the continents of Asia, Europe, and Africa.Islam has been very strong because they have been the leading nation in the Islamic world for hundreds of years (Mukhsin, 2009;Putri et al., 2021).As with the previous Islamic government, the Turkish government was also led by a caliph who, besides acting as a state leader, was also a religious leader (Rahman, 2014).Even though the Ottoman Empire was more inclined towards politics and the military in its development, it cannot be denied that much progress was made during the reign of this Islamic empire, including in the arts (Muvid, 2022).
Etymologically, calligraphy comes from Latin, namely kallos means beautiful, and graph means writing.In Arabic, it is called khat which means lines or beautiful writing.
Meanwhile, in English, it is called calligraphy.So calligraphy can be interpreted as the ability to write beautifully (Sirojuddin, 2016).In terminology, calligraphy is a series of hijaiyah letters which contain verses from the Qur'an, Hadith, and sentences of wisdom written with the right proportions, both the spacing and the accuracy of the letter units (Oktaviana, 2022).Islamic calligraphy originating from the Arab world is the development of the beautiful art of Arabic letters, occupying the highest position compared to other Islamic arts because it is the only Islamic art produced by Islam itself.Calligraphy reflects the depth of art, and its essence comes from the values and concepts of faith (Fitriani, 2011;A. Hakim, 2021).Calligraphy is the science of knowing the state of each letter such as its placement and arrangement.Calligraphy is not only good writing, but calligraphy is a scientific discipline with certain procedures (Suharno & Mukhtarom, 2020).
Types of calligraphy or khat are Naskhi, Tsuluts, Riq'ah, Diwani, Kufi, and Farisi (Solikhin & Rahmi, 2018).First, Naskhi, namely writing that is cursive and easy to read, generally used in writing the Qur'an.Second, Tsuluts are widely used in book titles, chapter titles, and mosque wall decorations.Third, Riq'ah, namely writing that tends to be round in shape and the letters are short.Fourth, Diwani, namely writing that is circular in shape, stacked, the letters overlap, flexible and free.This khat is divided into two, namely the Diwani and the Diwani Jali which developed during the Ottoman Empire.Fifth, Kufi, namely Arabic writing in the form of a square.Sixth, Farisi, namely a form of writing that is slightly inclined to the right, often the letters do not have the same width (Sirojuddin, 2016;Yulika, 2016).The sixth types of writing are the main script or called al-Aqlam al-Sittah.Some add the Ijazah as a seventh type, and some exclude Farisi khat from the main type of calligraphy because they are considered not originally Arabic (Damit et al., 2021) This paper is different from previous studies.This paper emphasizes more on the forms, factors, and implications of Ottoman Empire calligraphy.While other articles review discussing the history of the development of calligraphy in general since calligraphy first appeared.First, writing (Sirojuddin, 2016) examines the art of calligraphy in general and the history of its development since it first appeared.The article focuses more on the types of Arabic calligraphy and the rules of writing.Second, writing (Yulika, 2016) also examines Islamic art and its history.This paper also mentions a little about the history of calligraphy during the Ottoman Empire but does not explain it in depth.Third, some articles discuss calligraphy during the Ottoman period but only focus on the role and contribution of Sultan Muhammad Al-Fatih to the development of calligraphy which shows that the government's role in the development of science is also very much needed (Ishak, 2022).The aspects of the study of these studies are the same as the author's research, namely calligraphy, but this research further strengthens the findings of the studies mentioned above.
The study of the history of Islamic civilization during the Usmani Turk period has three objectives: First, to understand the concrete form of calligraphy art during the Ottoman Empire period because at that time calligraphy became one of the Islamic arts that were in great demand and respect.Second, wanting to understand the factors causing the advancement of calligraphy art during the Ottoman Empire period which made it still exist among the Turks even though it was not the result of their original art but they were able to adopt it by developing it into a khat art that was even used by the Ottoman Empire rulers.Third, want to understand the implications of the advancement of the art of calligraphy on Islamic civilization in the time of the Ottoman Empire, where the Turkish state today is known as a country rich in historical heritage in world Islamic civilization.Thus, it can be a reflection that in the past there has been a story that deserves our study to design and can plan carefully for a brighter future without being shaken by any force.
This paper is based on three arguments, namely: First, the Ottoman Empire was an Islamic caliphate that was in power for a long time and had a great influence on civilization in the Islamic world including art (Duriana, 2018).Second, the Ottoman Empire civilization made Islam a symbol of solid strength capable of regrouping Muslims after experiencing setbacks (Uliyah, 2021).Third, Turkey Usmani is an Islamic caliphate that incarnates as a world superpower that manages the order of society by promoting a system of tolerance between religions (L.Hakim, 2019).Islam grew and developed not only as a belief but also as a civilization that had many empires or kingdoms after the death of Prophet Muhammad SAW (Amin & Ananada, 2018).The history of Islamic civilization today has been going on for more than fourteen centuries.As with the history of every people, the history of Islamic civilization has also experienced ups and downs.In certain periods Islam experienced growth and development, progress and glory, then in other periods, Islam experienced decline and even destruction (Asra et al., 2018).

Research Methods
The research method used in this study is the historical method.The sources used in this research are books and journals related to research on the history of the Ottoman Empire.The steps in historical research include four steps, namely: 1) Heuristics, at this stage researchers search for and collect traces of the Ottoman Empire by studying reading sources consisting of reference books and scientific journals.In this research study, researchers found that the sources used came from electronic and non-electronic books and journals related to research on several journal websites.2) Criticism of sources, at this stage the sources that have been obtained are analyzed first before being used both externally and in the content of related sources.In this source criticism, there are two, namely external criticism and internal criticism.In external criticism, the researcher tries to consider whether the source is appropriate or not to be used in the study.Meanwhile, in internal criticism, the researcher analyzes the content of the selected sources by checking their suitability to the research topic.
3) Interpretation, at this stage the researcher interprets the data and information found from these sources.Researchers construct narratives based on findings and try to understand historical events and their context.4) Historiography is the last step in writing this historical research.In terms of this historiographical step, the researcher is trying to determine a causal relationship from the history of calligraphy in the Ottoman Empire.

Forms of Calligraphy in the Ottoman Empire
The concrete form of calligraphy art at this time can be proven in three concrete forms, namely: First, the use of calligraphy in writing the Qur'an.The writing of the Qur'an during the Ottoman period was pioneered by Hamdullah Al-Amasy (1436-1520) using khat Naskhi, then continued and developed by Darwisy Ali and Hafidz Usman (Hidayat, 2017).There are 25 Al-Qur'an manuscripts handwritten by Hafidz Usman which have been printed and circulated hundreds of times in various Islamic countries.The manuscripts he wrote are among the most beautiful manuscripts ever written because they have clear letters, beautiful arrangements, and are easy to read (Nur, 2018).Second, the ornaments on religious buildings, such as those in the Hagia Sophia Mosque and the Blue Mosque.At the Hagia Sophia Mosque, calligraphy is used as a cover for Christian images (Awaliyah, 2020;Muhammad et al., 2020).Meanwhile, at the Blue Mosque calligraphy is found on the interior and exterior of the mosque.The calligraphy is the work of Seyyid Kasim Laubari (Andriyani, 2020).Third, the calligraphy school was founded by Syaikhul Islam Hayri Efendi (1869-1922) free of charge from students (Derman, 2007).It is not surprising that the city of Istanbul, which was the administrative center of the Ottoman Turkish government, became the center for the development of calligraphic art.In that city, the most beautiful and highest-quality calligraphic works appeared.When Sultan Muhammad Al-Fatih was in power (1444-1446 and 1451-1481), he paid great attention to fine art in general and calligraphy in particular.This can be seen from the large collection of calligraphy writings written by Sheikh Hamdullah, a genius calligrapher at that time.These works were placed in the Sultan Muhammad Al-Fatih Library by his son, Prince Bayazid.Apart from that, there are inscriptions in Jeli Sulus which were written in calligraphic style by two calligraphy masters, namely Yahya Sofi and Ali Sofi (Hafil, 2020).
Based on the description above, it can be understood that calligraphy is one of the artistic heritages in Islamic culture, for example we often find it on the walls of mosques, handicraft products decorated with calligraphy, calligraphic works that are often presented at cultural events and Islamic festivals, such as midnight takbiran, Nuzulul Qur'an commemoration and others.Calligraphy during the Ottoman Empire experienced rapid development, during which time calligraphy was in demand by all circles, not only by ordinary people but also the sultans so that several sultans at that time were known as calligraphers.The works of calligraphers from that period still survive today.The forms of calligraphy based on the data above show the use of calligraphy during the Ottoman period showed diversity, not only used for writing the Qur'an but also as decorations in various Ottoman buildings which made it have a very high artistic beauty value.This shows that the Ottoman Turks created many innovations in the art of calligraphy.The art of calligraphy which was originally used to write the Qur'an has developed widely in Islamic society with a great variety.Various types of khat in calligraphy are used as ornaments for religious buildings as a form of expressing Islamic spiritual values.
In various literature it is described that Arabic writing which later became the basic pattern of Arabic calligraphy, was originally only in the form of lines or strokes and in the end became an inscription that was poured in various media such as stone, metal skin, wood and other objects (Anwar, 2018).Calligraphy is a field of expression for the soul of Muslim artists as long as these expressions do not deviate from or conflict with Islamic law which includes aspects of morality, faith, and philosophy of human life (Jinan, 2010).All types of calligraphy have a function of beauty and become a means of displaying metaphysical messages written in their culture.Calligraphy is an important part of religious, social, political, and cultural life, because of the importance of this field of art Arabic calligraphy has always been a concern, knowledge, and skill among Muslims.

Factors in the Development of Ottoman Turkish Calligraphy
Three factors influenced the progress of Ottoman Empire calligraphy, namely: First, the religious spirit of the Turkish nation which was inspired by the Qur'an.The proof lies in the fact that calligraphy experts inscribe verses from the Quran as both adornments and religious symbols in mosques.The purpose of calligraphy is not solely to create beautiful decorations; rather, it serves to remind humanity to remain faithful and to live their lives in accordance with the teachings of the Quran (Hafil, 2020).Calligraphy cannot be separated from the spirit of Islam.Islamic calligraphy is based on the Qur'an as an expression of the artistic and aesthetic feelings of the calligrapher's soul which makes them write the Qur'an using various types of khat such as Naskhi, sulus, and Diwani (Setiawan, 2016).
Second, the Turkish people's love for calligraphy.Their affection for calligraphy began in the 10th century when they migrated and interacted with the Arab communities.The Turkish people migrated to the regions of Turkestan, Afghanistan, and Iran, where a significant portion of them had already embraced Islam as their religion.As a result of this contact, many Turkish individuals converted to Islam.After becoming Muslims, their fondness for the Arabic language grew, and gradually, they abandoned the old Uighur script that they had been using.They began to use the Arabic script, which they continued to use for approximately a thousand years until the emergence of a new Turkish script in 1928 (Ash-Shalabi, 2003;Sasongko, 2018).Despite having their own script, the Turkish people's love for the Arabic language and its script remained strong.This is evidenced by the fact that during the Ottoman Empire era, the Turkish language was rich in Arabic vocabulary, comprising approximately 88% of its lexicon.The language incorporated numerous loanwords from Arabic and Persian and was written in the Arabic script (Wikipedia).
Third, support from the Ottoman Turks.The Ottoman Empire leaders who greatly supported and paid great attention to the art of calligraphy were Sultan Muhammad Al-Fatih, Sultan Murad II, Sultan Bayazid II, Sultan Murad III, and Sultan Sulaiman II.The Ottoman rulers gave calligraphers space to be creative (A.Hakim, 2021;Ishak, 2022).Due to his love for calligraphy, the Sultan even took it upon himself to hold the inkwell while Syekh Hamdullah created his masterpiece with his strokes (Ishak, 2022).The role of kings and social elites in providing support also encourages calligraphy artists to develop their creativity.
Many innovations in calligraphy have been introduced to Muslims, not only developed in the form of beautiful writing with rules but also started to be developed in the context of art or visual arts.Renewal of interest and experimentation through beautiful writing is an encouraging sign for the future of Islamic art.
Based on the description above, it can be understood that the Qur'an is the beginning of all studies of calligraphy.Qur'anic quotations are a common and almost universal text upon which calligraphy is based.The development of the art of calligraphy is inseparable from Islamic civilization, especially in the Ottoman Empire, where the Ottoman community assimilated and continued the developmental relay of calligraphy imaginatively without any discrimination from the authorities.Calligraphy as the embodiment of the word of Allah SWT develops with various models as a form of appreciation by Muslims for Arabic writing so that the art of calligraphy continues to develop and does not rule out the emergence of reliable calligraphers.Through calligraphy, one can feel that the words of Allah SWT in the Qur'an not only radiate ideas but also radiate power from the reader.The values of the Qur'an applied in calligraphy can make readers understand and interpret life according to the verses written.However, Islamic calligraphy is not limited to religious subjects, objects, or aspects.Like all Islamic art, it contains a wide variety of works created in different contexts.
The factors above show that the development of Islamic calligraphy is very much tied to the Qur'an because the calligraphy inspiration comes from the Qur'an and has an impact on the spirit of Muslims.This was also stated by Dharun Sarif that the presence of various forms of calligraphy after the Qur'an was revealed did not only affect the spiritual aspects of Muslims but also had an effect on social and cultural aspects.The presence of the Qur'an not only adds to the beauty of calligraphy but also shapes the mindset of Muslims (Sarif, 2016).The history of Islamic art is closely related to the art of calligraphy in Turkey, where cultural assimilation by the Turks made them continue the relay of Arabic calligraphy imaginatively without any discrimination from the authorities.So they became famous for their love of Islamic arts.This is in line with the opinion that calligraphy during the Ottoman era was inseparable from government support (Yulika, 2016).

Implications of the Development of Ottoman Turkish Calligraphy
The implications of the progress of calligraphy during the Ottoman Empire are: First, the emergence of a new style in calligraphy in the early 15th century.Among the popular styles are Syikastah, Syikastah-amiz, Diwani, and Diwani Jali.This style was developed by Ibrahim Munif, then refined by Syaikh Hamdullah (Huda & Muharsafa, 2010).Apart from that, the Tugra khat also developed, which is a combination of Diwani and diploma khat, and became the pride of Ottoman Empire calligraphers.This writing symbolizes wisdom (Hidayat, 2012;Yulika, 2016).Second, Istanbul became the center of Islamic calligraphy.Istanbul is the capital of Turkey, formerly known as Constantinople.After the conquest of Constantinople, Muhammad Al-Fatih then transformed the city into a symbol of Islamic culture.Various religious foundations and mosques are decorated with calligraphic ornaments.Istanbul is recognized by the world as the center of calligraphy so it becomes a reference for everyone in various countries to learn the art of calligraphy (Laveda, 2022).People from all around flock to Istanbul to study the art of calligraphy.The greatest calligraphic works produced can be seen at the Topkapi Palace Museum and the Museum of Turkish and Islamic Art (Hafil, 2020).Third, calligraphy is one of the media for learning mathematics.Unknowingly learning calligraphy, indirectly we have learned mathematics.Several techniques in calligraphy writing reflect or are related to mathematics, such as symmetry, angles, flat shapes, and others (Auliya, 2018).
Based on the description above, it can be understood that the progress of calligraphy has had a positive impact on Islamic civilization in Turkey and even today's civilization.Calligraphy has a very important role in the development of the Islamic world and science, becoming an identity and symbol of the reality of Islamic culture.These advances have had an impact on the development of Turkish calligraphy and capital styles which are even recognized by the whole world.In a proverb, it is stated that "the Koran was revealed in the Hijaz, recited in Egypt, and written in Istanbul".This shows that calligraphy is highly respected in Turkey and even today we can still see the works of Ottoman Empirecalligraphers.Not only that, calligraphy as a cultural heritage can also be used as a learning medium that can attract the attention of students such as in mathematics, so students will not feel bored during the learning process.This is one form of creativity and innovation of educators in learning so that they can bring students to recognize the environment and culture around them.
After going through a long history, calligraphy in Turkey was enriched with the discovery of new styles with distinctive characteristics and parts of these new forms.During the Ottoman era, the Syikasteh style was used for personal correspondence, business, and as the handwritten script for Persian and Urdu.Syikasteh Amiz, on the other hand, was employed for royal and business tasks.This style of calligraphy is wider and less dense compared to Syikasteh and is typically written on ornamental and colored paper (Alashari et al., 2019;Amani & Drav, 2021).Meanwhile, Diwani was used for writing administrative purposes in the offices of the Ottoman Empire, while Diwani Jali was solely used for decoration (Amrulloh et al., 2022).As time has progressed, these styles have been combined with geometric forms and natural shapes.Even today, there is a creative artistry in calligraphy that involves various styles and distinctive characteristics in the craft of calligraphy, sometimes incorporating elements of geometry and the natural world (Khoiri, 2019).This is an innovative calligraphic effort that is applied in ornamental styles and designs to give an aesthetic impression to the audience.This is in line with the opinion that calligraphy has a very important role in the development of the Islamic world and science, becoming an identity and symbol of the reality of Islamic culture.Calligraphy reflects the characteristics of a cultured person which encompasses the discipline of the mind, soul, and power.then there is no doubt that calligraphy is known as the art of Islamic (Islamic art) (Mazawa, 2016).J Pedersen ensures that no script in this world has become an object of great artistic art like the Arabic script.It has very beautiful and noble forms artistically or even each letter has a philosophical and spiritual meaning.Calligraphy is an artistic heritage from ancient times which until now can be enjoyed by its beauty (Yassir, 2021).
Thus, calligraphy has made a positive contribution to Islamic civilization and will continue to evolve in various forms as an expression of appreciation by Muslims for the beauty of Arabic script.The reign of the Ottoman Dynasty marked a glorious era for the development and advancement of Islam, particularly in the realm of calligraphy.During the Ottoman rule, calligraphy became the most prominent art form.Many renowned calligraphers emerged during this period, producing a wide range of calligraphic artworks, the beauty of which can still be appreciated today.Calligraphy, as an aesthetic discipline, embodies high cultural values and educational principles derived from religion, society, economics, and more, serving as a medium for scholarly research and scientific inquiry.
Calligraphy has aesthetic value so that its beauty can attract the attention of the Ottoman Turks in particular and Muslims in general to maintain the existence of the Qur'an.It is not surprising that throughout the history of Muslim respect for calligraphy is much higher than for other types of art.The influence of the Al-Quran on the development of calligraphy can be seen in several verses which indicate the importance of writing.Symbolically, the Qur'an mentions qalam in the verses first revealed to the Prophet, namely in surah Al-'Alaq 1-5.In this way, the Al-Quran provides a ready-made source of logical inspiration for aesthetic creations.The aesthetics of the growth of calligraphy after the Al-Quran came down shows the maturity of beautiful works of art.If art is interpreted as something beautiful, and if beauty is interpreted as an expression of ideals, perfection, and as manifestation of a clear sense, then almost all types of Arabic calligraphy exhibit the values of beauty as works of art.
Based on this article, the following implications can be stated: First, theoretically, this paper is expected to broaden the body of knowledge and become a reference in tracing the historical picture of Islamic civilization during the Ottoman Empire (1299-1922 AD), especially regarding the art of calligraphy.Besides that, it can also make a major contribution to the art of calligraphy in Indonesia because it has very rich and endless decorative possibilities.As previously written, the implications of the form of the development of calligraphy have an impact on the development of learning media in formal education.Second, practically this writing is also expected to be a useful tool for implementing the art of calligraphy as a worldly reflection on God's word in Lauh Mahfuzh, which voices and describes the response of the human soul to Divine messages and is a visualization of the spiritual realities contained in Islamic revelation.Third, institutionally, the results of this paper are expected to provide information as a basis for consideration, support, and contribution to the development of Islamic calligraphy.
Three things can be formulated to learn from the development of calligraphy during the Ottoman Empire, namely: First, the current government can apply positive things to build and develop Islamic art, especially calligraphy.Second, in the field of calligraphy education can be used as a medium for formulating mathematics.In addition, it contains the value of Islamic education.These values can be implemented to achieve the goals of Islamic education, namely the transformation of human personality into a Qur'anic generation.Third, in the religious field, calligraphy can be used as a medium of da'wah to convey Kalamullah.

Conclusion
There are three important findings in this study, namely: First, Islamic calligraphy is not limited to religious aspects but reflects the depth of the meaning of art, whose essence comes from the values and concepts of faith.It contains various kinds of works made in different contexts.Second, the Islamic spirit, love of culture, and support from the government are factors that support the progress of an art form in a country.Quality calligraphy paintings will be able to bring the viewer to a transcendental awareness that above this life, there is someone who is very close and His grace always flows endlessly, namely Allah.Third, the implications of the development of calligraphy did not only have an impact on Islamic civilization during the Ottoman Empire but still exist today and contain cultural and educational values that can influence the development of education.Culture-based learning prioritizes student activities with a variety of cultural backgrounds that are owned, integrated into the learning process of certain fields of study, and can be developed based on the development and cultural heritage of the local community, one of which is through calligraphy.The researcher realizes that the results of this study have many limitations because: First, it only discusses three things, even though there are at least ten elements of history: important events in the past, regarding the place of events, time, phases, figures who played a role, works and achievements that need to be explored lessons that can be taken, historical criticism, and so forth.While this paper is limited to discussing the concrete form of the development of calligraphy during the Ottoman Empire, the factors of its development and implications that still need to be developed in further research so that the picture obtained is more holistic (intact).Second, time constraints.This research was conducted on a limited basis according to needs related to research only and seemed rushed because of the implementation of library research.Third, limitations in research design, and research implementation cannot be separated from knowledge, thus researchers are aware of the limitations in making scientific work, but continue to try to provide the best according to the scientific abilities of researchers so that further research needs to be carried out to deepen information and related literature.