The record of the strata exposed in the Grand Canyon, in Agar, W.M., Flint, R.F., and Longwell, C.R., compilers, Geology from original sources

Powell, J.W., 1929, The record of the strata exposed in the Grand Canyon, in Agar, W.M., Flint, R.F., and Longwell, C.R., compilers, Geology from original sources: New York, Henry Holt and Co., p. 416-424.