Creswell,John W. (2009). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (3rd.). Sage.
Lua i Stíl Chicago (17ú heag.)Creswell,John W. Research Design: Qualitative, Quantitative, and Mixed Methods Approaches. 3rd. New Delhi: Sage, 2009.
Lua MLA (9ú heag.)Creswell,John W. Research Design: Qualitative, Quantitative, and Mixed Methods Approaches. 3rd. Sage, 2009.
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