Essen, Donald, and Luqyana Luqyana. “Analysis and Dynamic Behavior of Portal Structure Due Rotating Machines Loads”. Journal of Applied Science, Engineering, Technology, and Education 1, no. 2 (January 16, 2020): 131-140. Accessed May 7, 2021. https://jurnal.ahmar.id/index.php/asci/article/view/40.