Knowlton, F.H. (1926). "Flora of the Latah Formation of Spokane, Washington, and Coeur d'Alene, Idaho". Shorter contributions to general geology, 1925(PDF) (Report). Professional Paper. Vol. 140. United States Geological Survey. pp. 17–55, plates VIII-XXXI. doi:10.3133/pp140A.
Knowlton, F.H. (1926). "Flora of the Latah Formation of Spokane, Washington, and Coeur d'Alene, Idaho". Shorter contributions to general geology, 1925(PDF) (Report). Professional Paper. Vol. 140. United States Geological Survey. pp. 17–55, plates VIII-XXXI. doi:10.3133/pp140A.