Robbins, Stephen L. <br/><br/>
Gravity and aeromagnetic studies of the Powder River Basin and surrounding areas, southeastern Montana, northeastern Wyoming and western South Dakota / 
Stephen L. Robbins 
 - Washington D. C. :  U. S. Government Printing Office,  1994. 
 - iv, 17 p. :  ill ;  27 cm 
 - U. S. Geological Survey bulletin ;  1917-R .
<br/><br/> PTSL : including Map