Dunphy, Dexter C.
McGraw-Hill, 1985
Buku Teks
Beard, Adrian
Routledge, 2004
Buku Teks SO
Cooper, Robert L.
Cambridge University Press, 1989
Buku Teks SO
Aitchison, Jean, 1938-
Cambridge University Press, 2001
Buku Teks SO
T.E. McAuley
Curzon Press, 2001
Buku Teks SO