Carvan, John, author
LBC Information Services Holmes Beach, 1997
Buku Teks
Lawson, R.G., author
Butterworth-Heinemann, 1992
Buku Referensi
Twomey
South-Western Co, 1987
Buku Teks
Kinder, Peter D.
McGraw-Hill, 1988
Buku Teks
Soulsby, J., author
McGraw-Hill, 1995
Buku Teks