Greif. The Age of the Crisis of Man. Princeton University Press.
Lua i Stíl Chicago (17ú heag.)Greif. The Age of the Crisis of Man. Princeton University Press.
Lua MLA (9ú heag.)Greif. The Age of the Crisis of Man. Princeton University Press.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.