Gerring, John  <br/><br/>
Social science methodology:   a unified framework 

 - 2nd ed.- 
 - London:  Cambridge University Press,  2012 
 - xxv,495p.:  ill.;  25cm. 
<br/><br/><label>ISBN: </label>9780521115049 
<br/><br/><label>Subjects--Topical Terms: </label>
<br/><br/><label>LC Class. No.: </label>H61.G466