Creswell, J. W. (2011). Research Design (3rd.). Sage.
Lua i Stíl Chicago (17ú heag.)Creswell, John W. Research Design. 3rd. New Delhi: Sage, 2011.
Lua MLA (9ú heag.)Creswell, John W. Research Design. 3rd. Sage, 2011.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.