Johnson, Palmer O. <br/><br/>
Statistical methods in research. 

 - New York  Prentice-Hall  1949. 
 - 377 p. 
<br/><br/><label>LCCN: </label>49004316  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mathematical statistics<br/>Probabilities<br/>Research