Heider L.J. <br/><br/>
Theoretical Analysis 
Heider L.J., Simpson J.E. 
 - Philadelphia & London  W.B.Saunders Company  1967 
 - 379 p. 
<br/><br/> Saunders Mathematics Books 
<br/><br/><label>Dewey Class. No.: </label>517.1/Berb.