1. Sheffer, H.W. (1968), Copper leaching practices in the Western United States. Information Circular no. 9341. Bureau of Mines, U.S. Dept. Interior. Washington DC.
2. Colmer, A.R. (1947), Science, 106, 253.
3. Bryner, L.C. (1954), Ind. Engr. Chem, 46 (12), 2587.
4. Bryner, L.C. (1957), Ind. Engr. Chem, 49 (10), 1721.
5. Zimmerley, S.R. (1958), U.S. Patent no. 2.829. 964.