Hyland, Ken, author
Longman, 2002
Buku Teks
McQuade, Donald, author
Alfred A. Knopf, 1983
Buku Teks
Flemming, Laraine E.
Houghton Mifflin, 1986
Buku Teks
Maimon, Elaine P., author
McGraw-Hill , 2003
Buku Referensi
Maimon, Elaine P., author
McGraw-Hill, 2002
Buku Teks