Bos, E.S. <br/><br/>
Cartographic principles in thematic mapping 

 - Irrigation department  Colombo 07  1973 
 - 110p.  fig. 
<br/><br/><label>Nat. Bib. No.: </label>6876 
<br/><br/><label>Subjects--Index Terms: </label>Mapping; Qualitative; Graphs 
<br/><br/><label>Universal Decimal Class. No.: </label>528.923  / BOS