Hidayati, Y. M. ., Sa’dijah , C. ., & Abd Qohar, . S. (2019). Combinatorial Thinking to Solve the Problems of Combinatorics in Selection Type. International Journal of Learning, Teaching and Educational Research, 18(2), 65–75. Retrieved from http://ijlter.myres.net/index.php/ijlter/article/view/595