Parker, Raymond L. <br/><br/>
Geochemistry of Niobium and Tantalum / 
by Raymond L. Parker and Michael Fleischer. 
 -- Washington :   United States Government Printing Office,   1968 
 - 43 p. -- 
 (Geological Survey Professional Paper  ; 612).
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geoquímica
<br/><br/><label>Universal Decimal Class. No.: </label>550.4