Distribution and stratigraphic correlation of Upper Palcocene and Lower Eocene fossil mammal and plant localities of the Fort Union, Willwood, and Tatman Formations, Southern Bighorn Basin, Wyoming / 
by Thomas M. Bown... [et.al.] 
 - Washington :  U.S. Government Printing Office,  1994 
 - 103 p. :  ill. ;  27 cm. 
 - U.S. Geological Survey professional paper ;  1540 .