Gaya APA

Creswell, J, W., Creswell, J, D. (2018). Research Design : Qualitative, Quantitative, and Mixed Methods Approaches . United States: SAGE Publications Inc.

Gaya MLA

Creswell, John, W.., Creswell, J., David. "Research Design : Qualitative, Quantitative, and Mixed Methods Approaches". United States: SAGE Publications Inc, 2018. Text.