Barnes, Ralph Mosser. <br/><br/>
Work sampling / 
Ralph M. Barnes. 
 - 2nd ed. 
 - New York :  Wiley,  1957. 
 - 283 p. :  ill. 
<br/><br/><label>LCCN: </label>5710799 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Time study.<br/>Sampling (Statistics).