Oxford : Oxford University Press, 1995,
Buku Referensi
London: Tiger Books International, 1994,
Buku Referensi
Langenscheidt, 1993,
Buku Referensi
Prowe, Gunhild, author
Oxford University Press, 1995
Buku Referensi
Weis, Erich, author
National Textbook Company, 1993
Buku Referensi