Ratnaningsih, Dewi Juliah, Anang Kurnia, Asep Saefuddin, and I Wayan Mangku. 2022. “Mixed Models of Non-Proportional Hazard and Application in The Open Distance Education Students Retention Data”. Journal of the Indonesian Mathematical Society 28 (3):323-44. https://doi.org/10.22342/jims.28.3.1185.323-344.