WEBSTER, F.G.A. Robert <br/><br/>
The gemmologists' compendium 

 - 5th rev. ed. 
 - London  N.A.G.press Ltd.  1970 
 - 235 p. 
<br/><br/><label>ISBN: </label>31621 
<br/><br/><label>Dewey Class. No.: </label>553.8  / WEB