Judd, Charles M. <br/><br/>
Research methods in social relations 
Charles M. Judd, Eliot Smith and Louise Kidder. 
 - 5th ed. 
 - Islamabad  National Book Foundation  1991. 
 - 563 p.  ill.  24 cm. 
<br/><br/><label>ISBN: </label>0030311497