Harary, Frank. <br/><br/>
Structural models:  an introduction to the theory of directed graphs/ 
[by] Frank Harary, Robert Z. Norman [and] Dorwin Cartwright. 
 - New York:  Wiley,  [1965]. 
 - ix, 415 p.:  illus.,  24 cm. 
<br/><br/>Bibliography: p. 392-395. 
<br/><br/><label>LCCN: </label>65012710 
<br/><br/><label>Nat. Bib. No.: </label>GB66-232 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Social sciences---Mathematical models.
<br/><br/><label>Dewey Class. No.: </label>519.535  / H254s