1. Antoro B, Margotomo W, Perdana A, Widijanto E, Wiwoho N, Ginting AP, Santosa RGI, Pramuji, Silaen H, Setyadi H, Iribaram F, Mundu S, Garjito W, Sumarwan F, Rohmadi A, Setiadi T, Afwan A, Asrizal, Pahala AR, Prasety N (2011) Geology and geotechnics of Grasberg open pit mining. PT Freeport Indonesia, Aksara Buana, Jakarta (in Bahasa Indonesia)
2. Barcelo MD, Nieber JL (1981) Simulation of natural soil pipes in a soil profile. In: Paper presented at the Summer Meeting. American Society of Agricultural Engineers, Orlando
3. Barcelo MD, Nieber JL (1982) Influence of soil pipe networks on catchment hydrology. Paper presented at the Summer Meeting, Am. Soc.Agric. Eng., Univ. of Wisc., Madison
4. Bedekar V, Niswonger RG, Kipp K, Panday S, Tonkin M (2012) Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW. Groundwater 50(2):187–198
5. Beveridge GSG, Schechter RS (1970) Optimisation. International student edition. McGraw Hill Inc, New York