National Geographic :  Kamchatka; Riddle of the Lusitania; John Wesley Powell; Chile´s Uncharted Cordillera Sarmiento 

 - [s.l.]:   National Geographic Society 
 - Mensual 
<br/><br/> INV. UNIV. 27848; INV. BIB. 26493 
<br/><br/><label>ISSN: </label>0027-9358 
<br/><br/><label>Standard No.: </label>DGR-M16191