Kalia, W. S. ., D. Harjunowibowo, and Lenny. “Sales People Training Programme Scheduling Using Multiple Objective Linear Programming: Case Study of an Indonesian Motorcycle Distributor”. Journal of Mobile Multimedia, vol. 14, no. 1, Apr. 2018, pp. 75-94, https://journals.riverpublishers.com/index.php/JMM/article/view/4433.