Lenk, John D., author
McGraw-Hill, 1994
Buku Referensi
Holland, Patricia, author
Routledge, 1997
Buku Referensi
edited by Jerry C. Whitaker
CRC Press, 2002
Buku Referensi
Vinogradov, N.
Peace, [date of publication not identified]
Buku Teks
Carey, James
Wiley Publishing, Inc., 2000
Buku Teks