Parker, Raymond L. <br/><br/>
Geochemistry of niobium and tantalum / 
by Raymond L. Parker and Michael Fleischer 
 - Washington :  United States Government Printing Office,  1968 
 - iii, 43 p. ;  ill. ;  29 cm. 
 - United States. Geological Survey. Professional paper ;  612 .
<br/><br/>Includes bibliographies 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Niobium<br/>Tantalum
<br/><br/><label>Dewey Class. No.: </label>546.524