Helly, Walter, <br/><br/>
Urban systems models / 
Walter Helly. 
 - New York :  Academic Press,  1975. 
 - x, 185 pages :  illustrations ;  24 cm. 
 - Operations research and industrial engineering .
<br/><br/>Includes bibliographies. 
<br/><br/><label>ISBN: </label>0123394503 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Cities and towns--Mathematical models.