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, D.C. :  United States Government Printing Office,  1968 
 - iii, 22, [5] p. :  ill. ;  29 cm. 
 - Geological Survey professional paper ;  no.594-L Shorter contributions to general geology .
<br/><br/>Bibliography: p. 18-20 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geology, Stratigraphic--Cretaceous<br/>Phosphates--Black Hill<br/>Phosphates--South Dakota<br/>Geology--Black Hills<br/>Geology--South Dakota
<br/><br/><label>Subjects--Geographic Terms: </label><br/>Niobrara Formation
<br/><br/><label>Dewey Class. No.: </label>551.8975243