West-east stratigraphic transect of Cretaceous rocks in the northern Rocky Mountains and Great Plains regions, southwestern Montana to southwestern Minnesota - Dyman, T.; Porter, K.; Tysdal, R.; Cobban, W.; Fox, J.; Hammond, R.; Nichols, D.; Perry Jr., W.; Rice, D.; Setterholm, D.; Shurr, G. W.; Haley, J.; et al. (IMAP, 1995)