Creswell, J. W. (2013). Research Design: Qualitative , Quantitative & Mixed Methods Approaches (3rd ed.). sage.
Chicago Style aipamenaCreswell, John W. Research Design: Qualitative , Quantitative & Mixed Methods Approaches. 3rd ed. New Delhi: sage, 2013.
MLA aipamenaCreswell, John W. Research Design: Qualitative , Quantitative & Mixed Methods Approaches. 3rd ed. sage, 2013.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.