The international system :  theoretical essays / 
edited by Klaus Knorr and Sidney Verba. 
 - USA :  Princeton university press,  1961. 
 - 237 p. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>international relation 
<br/><br/><label>Dewey Class. No.: </label>327  / KNO.I