Research design    :qualitative, quantitative, and mixed method approaches 
Cresswell,John W 
 - 3rd Edition 
 - Los Angeles  Sage publication  c2009 
 - xxix, 260 p. ;   26 cm 
<br/><br/>  Includes bibliographical references and index 
<br/><br/><label>ISBN: </label>9781412965569 9781412965576 
<br/><br/><label>LC Class. No.: </label>H62  / .C6963 2009