Iqbal, M., Nana Suwarna, Ildrem Syafri, and Winantris Winantris. 2014. “Eo-Oligocene Oil Shales of the Talawi, Lubuktaruk, and Kiliranjao Areas, West Sumatra: Are They Potential Source Rocks?”. Indonesian Journal on Geoscience 1 (3):135-49. https://doi.org/10.17014/ijog.1.3.135-149.