Tillich, P. The Protestant era. University of Chicago press.
Lua i Stíl Chicago (17ú heag.)Tillich, Paul. The Protestant Era. Illinois: University of Chicago press.
Lua MLA (9ú heag.)Tillich, Paul. The Protestant Era. University of Chicago press.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.