De Kun, Nicolas <br/><br/>
The Economic Geology Of Columbium (niobium) And Tantalum 

 -  SEGEMAR  1962 
<br/><br/> Economic Geology, Volumen 57, Pags. 377-404 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geologia Economica