Little, Brown & Co., 1982
Buku Teks
Laski, Harold J., author
George Allen and Unwin, 1960
Buku Teks
Ballinger Publishing Company, 1981
Buku Teks
Coplin, William D.
Duxbury Press, 1974
Buku Teks
Leege, David C., author
Yayasan obor Indonesia, 2006
Buku Teks