Becker, George Joseph, author
Frederick Ungar Publishing, 1983
Buku Teks
Statler, Oliver
Charles E. Tuttle Co., 1956
Buku Teks
Michener, H. Andrew
Harcourt Brace Jovanovich, 1986
Buku Teks
Dupee, F.W., author
Doubleday, 1956
Buku Teks
Swan, Michael, author
Longmans, 1950
Buku Teks