Duncan, F.G.
Prentice-Hall, 1979
Buku Teks SO
Ince, Darrel
Oxford University Press, 1988
Buku Teks SO
Duncan, FG.
Prentice-Hall, 1979
Buku Teks SO
Massa, Anthony J.
Prentice-Hall, 2003
Buku Teks SO
edited by Cliff B. Jones, Roger C.F. Shaw
Prentice-Hall, 1990
Buku Teks SO