Harnack, A. (1957). What is Christianity? Harper & Brothers.
Lua i Stíl Chicago (17ú heag.)Harnack, Adolf. What Is Christianity? New York: Harper & Brothers, 1957.
Lua MLA (9ú heag.)Harnack, Adolf. What Is Christianity? Harper & Brothers, 1957.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.