Creswell, John W. Research design : qualitative, quantitative, and mixed methods approaches / John W. Creswell - 3rd ed. - New Delhi : Sage, c2009. - xxix, 260 p. ; 26 cm. ISBN: 9781412965576 LCCN: Subjects--Topical Terms: Social sciencesResearchMethodology LC Class. No.: H62 / .C6963 2009 Dewey Class. No.: 300.72 / C923r