Ryder, Nicholas
Cambridge University Press, 2012
Buku Teks SO
Savage, Nigel
Butterworth, 1991
Buku Teks
Hewiit, Charles M.
Houghton Mifflin, 1962
Buku Teks
Simpson, Laurence P.
Alexander Hamilton Institute, 1961
Buku Teks
Goode, Roy
Penguin Books, 2004
Buku Teks SO