Syafri, I., Sudradjat, A., Sulaksana, N., & Hartono, G. (2010). The Evolution of Gajahmungkur Paleovolcano, Wonogiri, Central Java, as A Reference to Revize the Terminology of “Old Andesite Formation”. Indonesian Journal on Geoscience, 5(4), 263–268. https://doi.org/10.17014/ijog.5.4.263-268