Syafri, Ildrem, A. Sudradjat, Nana Sulaksana, and G. Hartono. “The Evolution of Gajahmungkur Paleovolcano, Wonogiri, Central Java, As A Reference to Revize the Terminology of ‘Old Andesite Formation’”. Indonesian Journal on Geoscience 5, no. 4 (December 28, 2010): 263–268. Accessed April 21, 2025. https://ijog.geologi.esdm.go.id/index.php/IJOG/article/view/109.