Feldstein, Paul J., author
Delmar, 1993
Buku Teks
Clewer, Ann, author
Pearson Education, 1998
Buku Teks
Mooney, Gavin H., author
Prentice-Hall, 1992
Buku Teks
Editor: Souzy Dracopoulou
Routledge, 1998
Buku Teks
Garrett, Thomas M., author
Prentice-Hall, 2001
Buku Teks