Gilbert, Mark
Hodder & Stoughton, 1999
Buku Teks
Chapin, Alex, author
McGraw-Hill, 2011
Buku Teks
Heilenman, L. Kathy.
Harper & Row, [date of publication not identified]
Buku Teks
Evelyne Amon
McGraw-Hill Companies, 1996
Buku Teks
Graham, Gaelle, author
Hodder & Stoughton, 1991
Buku Teks