Cary, Otis
Charles E. Tuttle, 1976
Buku Teks
Niebuhr, Reinhold, author
Charles Scribner's Sons, 1949
Buku Teks
edited by Robert E. Buswell, and Tomothy S. Lee
University of Hawai'i Press, 2006
Buku Teks
Niebuhr, Reinhold, author
Nisbet, 1947
Buku Teks
Harcnack, Adolf, author
Harper & Brathers, 1957
Buku Teks