1. H. Palar, Pollution And Heavy Metals Toxicology, Jakarta, Indonesia, 2008, p. 152.
2. S.R. Untung, A.N. Yayat, Environtmental Problems Inventory of Society Gold Mining in Wonogiri Region, Geology Research Center and Development, Jakarta, Indonesia, 1999.
3. Giyatmi, Z. Kamal, D. Melati, National Seminar Proceeding IV SDM Nuclear Technology, Yogyakarta, Indonesia, 25-26 August 2008.
4. Extraction Equilibria of Copper(II) with D2EHPA in Kerosene from Aqueous Solutions in Acetate Buffer Media
5. Y.M. Khawassek, M.F. Cheira, G.M. Mahmoud, Res.J.Chem.Sci. 2/6: 30 (2012)