Ba’Its, Hamzah Abdul, Ika Arum Puspita, and Achmad Fuad Bay. “Combination of Program Evaluation and Review Technique (PERT) and Critical Path Method (CPM) for Project Schedule Development”. International Journal of Integrated Engineering 12, no. 3 (February 2, 2020): 68-75. Accessed June 25, 2021. https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/4207.