Richard, K.E., 1978, Thirty-year evolution of porphyry copper exploration in southwest USA; Part 1. Techniques and philosophies, in Jenney, J.P., and Hauck, H.R., eds., Proceedings of the Porphyry Copper Symposium, Tucson, Ariz., March 18-20, 1976: Arizona Geological Society Digest, v. 11, p. 169-174.
