Clyde, Paul H. (Paul Hibbert), author
Prentice-Hall, 1953
Buku Teks
Jolliffe, Jill
University of Queensland, 1978
Buku Teks
Walz, Jay, author
Atheneum, 1966
Buku Teks
Ward, Robert S., author
University of Chicago Press, 1945
Buku Teks
Hersey, John
Franklin Watts, 1944
Buku Teks