Megaflora of the Hell Creek and lower Fort Union Formations in the western Dakotas: Vegetational response to climate change, the Cretaceous-Tertiary boundary event, and rapid marine transgressionDOI: info:10.1130/0-8137-2361-2.329v. 361Geological Society of America329–391
Johnson, Kirk R. 2002. "Megaflora of the Hell Creek and lower Fort Union Formations in the western Dakotas: Vegetational response to climate change, the Cretaceous-Tertiary boundary event, and rapid marine transgression." In The Hell Creek Formation and the Cretaceous-Tertiary boundary in the northern Great Plains: An Integrated continental record of the end of the Cretaceous ; Special Paper 361. Hartman, Joseph J., Johnson, Kirk R., and Nichols, Douglas J., editors. 329–391. Geological Society of America. 361 https://doi.org/10.1130/0-8137-2361-2.329.