Nicholas A. Famoso, Darrin Pagnac. A Comparison of the Clarendonian Equid Assemblages from the Mission Pit, South Dakota and Ashfall Fossil Beds, Nebraska // Transactions of the Nebraska Academy of Sciences and Affiliated Societies 32, 2011. P. 98–107.URL: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1008&context=tnas
