Prof Hafiz Abdul Ahad <br/><br/>
Encyclopedia baraey keemiya (Jild Doim)   L say Z  

 -  Lahore  Urdu Science Board  2003 
 - Page 627 say 1231 
<br/><br/><br/>ur 
<br/><br/><label>Dewey Class. No.: </label>540.3  /  ABD