Juliani, R., T. Sembiring, M. Sitepu, and . Motlan. “Geophysical Study for Discovering The Missing of Lau Ketuken from The Surface at Sulkam Village”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 22, no. 1, May 2015, pp. 360-6, https://gssrr.org/index.php/JournalOfBasicAndApplied/article/view/4020.