Scholastic, 1982
Buku Teks
Swan, Michael, author
Cambridge University Press, 1992
Buku Teks
Sharpe, Pamela J., author
Barron's, 2001
Buku Teks
Sullivan, Patricia Noble, author
Macmillan Company, 1997
Buku Teks
Cambridge University Press, 2009
Buku Teks