Barone, Michael, author
National Journal, 1990
Buku Referensi
Pustaka Sinar Harapan; Media Interaksi Utama, 1991
Buku Referensi
edited by Anthony J. Kane
Westview Press, 1990
Buku Teks
Loo, L. Frank van, author
Boom, 1994
Buku Teks
Saso, Mary, author
Abt Books, 1982
Buku Teks