Ratnaningsih, Dewi Juliah, Anang Kurnia, Asep Saefuddin, and I Wayan Mangku. “Mixed Models of Non-Proportional Hazard and Application in The Open Distance Education Students Retention Data”. Journal of the Indonesian Mathematical Society 28, no. 3 (December 10, 2022): 323–344. Accessed October 5, 2024. http://jims-a.org./index.php/jimsa/article/view/1185.