Tourtelot, Harry Allison  1918- <br/><br/>
Stratigraphic significance and petrology of phosphate nodules at base of Niobrara formation, east flank of black hills, South Dakota / 
by Harry A. Tourtelot and W. A. Cobban. 
 -- Washington :   United States Government Printing Office,   1968 
 - 22 p., [2] h. de lam. -- 
 (Geological Survey Professional Paper  ;  594-L).
<br/><br/><label>Subjects--Topical Terms: </label><br/>Dakota del Sur<br/>Estratigrafía
<br/><br/><label>Universal Decimal Class. No.: </label>551.7(783)