Stratigraphic sections of the Phosphoria formation in Idaho, Montana, Utah and Wyoming - McKelvey, V.E.; Davidson, D.F.; O’Mally, F.; Smith, L.E.; Armstrong, F.C.; Sheldon, R.P.; Hoppin, R.A.; Gulbrandsen, R.; Campbell, R.M.; Swanson, R.; Klepper, M.; Lowell, W.R.; et al. (Open-File Report, 1951)