Hardy, R.H
Oxford University Press, 1987
Buku Teks SO
Hardy, R.H
Oxford University Press, 1987
Buku Teks SO
Brierley, Sean, 1966-
Routledge, 1995
Buku Referensi
Weinberger, Marc G.
Lexington Books, 1994
Buku Teks SO
Stansfield, Richard H.
The Dartnell Corporation, 1985
Buku Teks SO