Gaya APA

Creswell, J, W. (2009). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (3rd. ed). The United States: Sage Publication.

Gaya MLA

Creswell, John, W.. "Research Design: Qualitative, Quantitative, and Mixed Methods Approaches". 3rd. ed The United States: Sage Publication, 2009. Text.