Cutts, Martin, author
Oxford University Press, 1995
Buku Teks
Furness, Edna L.
Appleton Century , 1964
Buku Teks
Reader's Digest Service, 1987
Buku Teks
HarperCollins Publishers, 1993
Buku Referensi
Mudd, Norma
Hodder & Stoughton Educational , 1998
Buku Teks