Pounds, Norman J. G.
Frederick A. Praeger, 1964
Buku Teks SO
London Chancellor Press 1999,
Buku Referensi
Cribb, Robert Bridson
NIAS Press, 2010
Multimedia
Philips
Chancellor Press, 1999
Buku Referensi
Selmann, R. R.
Edward Arnold, 1953
Buku Referensi