Harary Frank, and others <br/><br/>
Structural models    An introduction to the theory of directed graphs    

 - New York  Wiley           1965 
 - ix,415p.  cm. 
<br/><br/> Bibliography: P 392-395; Glossary: P 404-410 
<br/><br/><label>Source: </label> General Book 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geometry
<br/><br/><label>Dewey Class. No.: </label>B6, K5