Lugton, Robert C.
Prentice-Hall, 1978
Buku Teks
Thomson, A.J., author
Oxford Oxford University Press, 1986
Buku Teks
Bowman, Phil
Nelson, 1989
Buku Teks
Swan, Michael, author
Cambridge University Press, 1992
Buku Teks
Hill, Robert J., author
Macmillan, 1982
Buku Referensi