Moriarty, Sandra E. (Sandra Ernst), author
Prentice Hall International, 1991
Buku Teks
St John, Maggie Jo
Prentice Hall ELT, 1994
Buku Teks
Berita Buana, 1977
Buku Teks
Wells, William D., author
Prentice-Hall, 2000
Buku Teks
Zyman, Sergio, author
John Wiley & Sons, 2002
Buku Teks