Aziz, A. et al. 2016. Implementasi Model Problem Based Learning (PBL) dalam Meningkatkan Kemampuan Berpikir Kritis Mahasiswa melalui Lesson Study. Jurnal Elemen. 2, 1 (Jan. 2016), 83–91. DOI:https://doi.org/10.29408/jel.v2i1.179.