Triswanto, H. “The Effect of Intrinsic and Extrinsic Motivation on Employee Performance Productivity PT. Timbang Deli Indonesia”. Journal of Management Science (JMAS), vol. 3, no. 4, Oct. 2020, pp. 115-21, https://www.exsys.iocspublisher.org/index.php/JMAS/article/view/64.