Nursing research  principles and methods 
Denise F. Polit, Bernadette P. Hungler. 
 - 6th ed. 
 - Philadelphia  Lippincott Rave Publishers  1999 
 - xviii, 757p., 24cm. 
<br/><br/><label>ISBN: </label>0-7817-1562-8. 
<br/><br/><label>Dewey Class. No.: </label>610.7307  / P65M