Ruffin, Roy,  1938- <br/><br/>
Principles of economics / 
Roy J. Ruffin, Paul R. Gregory. 
 - 5th ed. 
 - New York :  HarperCollins College Publishers,  c1993. 
 - xxxi, 850 p. :  ill. 
<br/><br/>Includes bibliographical references and indexes. 
<br/><br/><label>ISBN: </label>067346590X 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Economics.