Michael Wallace Gordon
St. Paul, Minn, 1996
Buku Teks
Wilcox, Clair, author
Macmillan, 1949
Buku Teks
Fisher, Bart S.
Little, Brown and Company, 1989
Buku Teks
Lepi T. (Tanadjaja) Tarmidi, author
UI-Press, 1995
Buku Teks
Brown, William Adams.
Washington, D.C., Brookings Institution
Buku Teks