Steingass, F., author
Cosmo Publications, 1985
Buku Referensi
Hunter, Lynne, author
Prentice Hall Regents, 1989
Buku Teks
Lugton, Robert C.
Prentice-Hall, 1978
Buku Teks
Tomasowa, Francien Herlen, author
Universitas Brawijaya , 2005
Buku Teks
Murphy, Raymond, author
Cambridge University Press, 1998
Buku Teks