Sudarsan, I W., E. T. Baskoro, H. Assiyatun, and S. Uttunggadewa. “/I>”;. Journal of the Indonesian Mathematical Society 15, no. 1 (May 7, 2012): 61–67. Accessed March 29, 2024. http://jims-a.org/index.php/jimsa/article/view/44.