Pennings, P. (2006). Doing research in political science (2nd ed.). Sage.
Lua i Stíl Chicago (17ú heag.)Pennings, Paul. Doing Research in Political Science. 2nd ed. London ; Thousand Oaks, Calif: Sage, 2006.
Lua MLA (9ú heag.)Pennings, Paul. Doing Research in Political Science. 2nd ed. Sage, 2006.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.