Perwitasari, D. and Surya, E. (2017) “The Development of Learning Material Using Problem Based Learning to Improve Mathematical Communication Ability of Secondary School Students”, International Journal of Sciences: Basic and Applied Research (IJSBAR), 33(3), pp. 200–207. Available at: https://www.gssrr.org/index.php/JournalOfBasicAndApplied/article/view/7382 (Accessed: 6 May 2024).