National Geographic :  Himalayan Caravans, The Superior way of Life, St. Petersburg, Capital of the Tsars, Passion Vine Butterflies 

 - Washington :   National Geographic Society 
 - Mensual 
<br/><br/> INV. UNIV. 27832; INV. BIB. 26489 
<br/><br/><label>ISSN: </label>0027-9358 
<br/><br/><label>Standard No.: </label>DGR-M16202