Foster, George M.
Harper & Row , 1962
Buku Teks
Smith, L. Glenn
Allyn and Bacon, 1973
Buku Teks
Cochrane, Willard W.
University of Minnesota Press, 1964
Buku Teks
Ellul, Jacques
Vintage Books, 1954
Buku Teks
Sahal, Devendra
Addison-Wesley, 1981
Buku Teks