Nursing research :  principles and methods / 
Denise F. Polit, Bernadette P. Hungler. 
 - 3rd ed. 
 - Philadelphia :  J. B. Lippincott,  1987. 
 - xvii, 571 p. :  ill. ;  25 cm. 
<br/><br/><label>ISBN: </label>0397546319 
<br/><br/><label>LC Class. No.: </label>RT81.5   / .P64 1991