Creswell, J. W. (2011). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (3rd ed.). SAGE Publications India Pvt. Ltd.
Lua i Stíl Chicago (17ú heag.)Creswell, John W. Research Design: Qualitative, Quantitative, and Mixed Methods Approaches. 3rd ed. New Delhi: SAGE Publications India Pvt. Ltd, 2011.
Lua MLA (9ú heag.)Creswell, John W. Research Design: Qualitative, Quantitative, and Mixed Methods Approaches. 3rd ed. SAGE Publications India Pvt. Ltd, 2011.
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