LoBiondo-Wood, Geri. 
Nursing research :  methods and critical appraisal for evidence-based practice /  Geri LoBiondo-Wood, Judith Haber.   - 6th ed.   - St. Louis, Mo. ;  [London] :  Elsevier Mosby,  2006.   - xx, 602 p. :  ill. ;  24 cm. +  1 CD-ROM.