Porteous, Andrew
John Wiley & Sons, 1992
Buku Referensi
McGraw-Hill, 2003
Buku Referensi
Brewer, Richard
Saunders College Publishing, 1994
Buku Teks SO
Ehrlich, Paul R.
Macmillan, 1987
Buku Teks SO
edited by Michael Allaby
Oxford University Press, 1994
Buku Referensi