Afina Aliyan, Silmi, et al. “Remote Sensing Data Integration of Landsat 8 and SRTM for Geomorphological Characteristics Identification in Karst Pringkuku, Pacitan, East Java”. International Journal on Advanced Science, Engineering and Information Technology, vol. 10, no. 1, Feb. 2020, pp. 212-8, doi:10.18517/ijaseit.10.1.6751.