Rudelius, William, author
Harcourt Brace Jovanovich, 1973
Buku Teks
Hidy, Ralph W
Haper, 1955
Buku Teks
Edwards, Corwin D., author
Press of Western Reserve University, 1956
Buku Teks
Warner, W. Lloyd, author
Harper & Brothers , 1955
Buku Teks
Edinburgh University Press, 2020
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