Leedy, P. D., & Ormrod, J. E. (2005). Practical research: Planning and design (8th ed.). Pearson/Merrill Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Leedy, Paul D., agus Jeanne Ellis Ormrod. Practical Research: Planning and Design. 8th ed. Upper Saddle River, N.J: Pearson/Merrill Prentice-Hall, 2005.
Lua MLA (9ú heag.)Leedy, Paul D., agus Jeanne Ellis Ormrod. Practical Research: Planning and Design. 8th ed. Pearson/Merrill Prentice-Hall, 2005.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.