1. Adji TN, Haryono E, Fatchurrohman H, Oktama R (2015) Diffuse flow characteristics and their relation to hydrochemistry conditions in the Petoyan Spring. Geosci J, Gunungsewu Karst, Java, Indonesia. doi: 10.1007/s12303-015-0048-8 (online first–In press)
2. Balazs D (1968) Karst regions in Indonesia: Karszt-Es Barlangkutatas, vol V. Budapest, Globus Nyomda, p 61
3. Bonacci O (1990) Regionalization in karst regions, Proceedings of the Ljubljana Symposium, April 1990, IAHS Publ. no. 191, 1990
4. Brunsch A, Adji TN, Ikhwan M, Stoffel D, Oberle P, Nestmann F (2011) Hydrological assessment of a karst area in Southern Java with respect to climate phenomena. Proceedings of Asian Trans-Disciplinary Karst Conference 2011, Jogjakarta, p 55–68
5. Budge TJ (2009) Modeling the usefulness of spatial correlation analysis on Karst systems. Groundwater 47:427–437