Purwanti, P., and M. . Sitorus. “Factors That Affect Employee Productivity (Case Study at PT. Sagami Indonesia)”. Journal of Management Science (JMAS), vol. 1, no. 1, Januari, Jan. 2018, pp. 7-11, https://www.exsys.iocspublisher.org/index.php/JMAS/article/view/2.