Erwin, Erwin, Muhammad Hayat, and Sutarno Sutarno. “Epistemologi Dan Keterbatasan Teori Gravitasi”. Titian Ilmu: Jurnal Ilmiah Multi Sciences 9, no. 1 (August 29, 2017): 33-40. Accessed October 28, 2021. https://journal.stkipnurulhuda.ac.id/index.php/JTI/article/view/79.