Cresswell, J. W. (2015). Research Design: Pendekatan kualitatif, kuantitatif, dan mixed. Pustaka Pelajar.
Lua i Stíl Chicago (17ú heag.)Cresswell, John W. Research Design: Pendekatan Kualitatif, Kuantitatif, Dan Mixed. Pustaka Pelajar, 2015.
Lua MLA (9ú heag.)Cresswell, John W. Research Design: Pendekatan Kualitatif, Kuantitatif, Dan Mixed. Pustaka Pelajar, 2015.
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