Johnson, Leonard G.. <br/><br/>
Theory and Technique of Variation Research /  

 - 1st ed /  
 - Amsterdam :   Elsevier Publishing Company. 
 - p.105 :  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Variation Research
<br/><br/><label>Dewey Class. No.: </label>B215  / K4