Levens, A. S. <br/><br/>
Graphical methods in research / 
[by] A.S. Levens. 
 - New York :  Wiley,  c1965. 
 - vi, 217 p. :  ill. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Graphic methods--Research.<br/>Statistics--Graphic methods.