Damayanti, Astrid, et al. “Potential Areas of Land Subsidence in Karst Landscape: Case Study in Ponjong and Semanu District, Gunungkidul Regency, Yogyakarta, Indonesia”. International Journal on Advanced Science, Engineering and Information Technology, vol. 11, no. 2, Apr. 2021, pp. 712-9, doi:10.18517/ijaseit.11.2.6754.