Slaff, Steven, Jackson, G.W., and Pearthree, P.A., 1989, Development of earth fissures in Picacho basin, Pinal County, Arizona from 1959 to 1989 [Newman Peak, Picacho Reservoir, Casa Grande Mtns., Eloy South, Eloy North, and Valley Farms 7.5 min]: Arizona Geological Survey Open-File Report 89-10, 38 p., 6 sheets, scale 1:24,000.