Brown, N.A., Mead, R.H., and McMurray, J.M., 1992, Relationship between collapse history and ore distribution in the Sage Breccia Pipe, northwestern Arizona, in Dickinson, K.A., ed., Short papers of the U.S. Geological Survey Uranium Workshop, 1990: U.S. Geological Survey Circular 1069, p. 54-56.