Alwadood, Zuraida, Hamidah Ayub, and Muhamad Ariff Izuddin Razali. “A Modified Integer Programming Model for Cleaning Service Scheduling”. Scientific Research Journal 7, no. 1 (June 1, 2010): 37–49. Accessed October 4, 2024. https://journal.uitm.edu.my/ojs/index.php/SRJ/article/view/3182.