Gaya APA

, ., Creswell, J, C. (2009). Research design: qualitative, quantitative, and mixed methods approaches . Los Angeles; SAGE, 2009: Los Angeles; SAGE, 2009.

Gaya MLA

, ., Creswell, John, C. "Research design: qualitative, quantitative, and mixed methods approaches". Los Angeles; SAGE, 2009: Los Angeles; SAGE, 2009, 2009. .