Sager, Naomi
Addison-Wesley, 1981
Buku Teks
Lyons, John, author
Cambridge University Press, 1991
eBooks
Parrot, Martin, author
Cambridge University Press, 2003
Buku Teks
Greenbaum, Sidney
Longman , 1990
Buku Teks
Krulee, Gilbert K., author
Prentice-Hall, 1991
Buku Teks