Sariningtias, R. ., N. . Kusumawardani, A. . Yasfi, A. . Syafaat, and R. . Aliyah. “Difficulty Analysis Learning Mathematics Society and Factors Cause for Junior Secondary Students”. Proceeding International Conference on Science and Engineering, vol. 3, Apr. 2020, pp. 635-8, doi:10.14421/icse.v3.578.