The ROI of human capital :  measuring the economic value of employee performance / 
Jac Fitz-enz. 
 - 2nd  ed. 
 - New York :  AMACOM,  2009. 
 - xxiii, 312  p. 
<br/><br/><label>ISBN: </label>0814413326 : 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Human capital.<br/>Labour economics.