Gray, Floyd, Miller, R.J., Hassemer, J.R., Knepper, D.H., Pitkin, J.A., Hanna, W.F., and Kreidler, T.J., 1989, Mineral resources of the Signal Mountain Wilderness Study Area, Maricopa County, Arizona, Chapter C, in Mineral resources of Wilderness Study Areas: Southwestern and south-central Arizona: U.S. Geological Survey Bulletin 1702-C, p. C1-C14.
