Ferkiss, Victor C.
Braziller, 1969
Buku Teks
Foster, George M., author
Harper & Row , 1962
Buku Teks
Smith, L. Glenn, author
Allyn and Bacon, 1973
Buku Teks
Cochrane, Willard W., author
University of Minnesota Press, 1964
Buku Teks
Ellul, Jacques
Vintage Books, 1954
Buku Teks