Partridge, Eric, 1894-1979
Penguin Books, 1982
Buku Teks SO
Howard, Godfrey
Pan Macmillan Publishers, 1993
Buku Referensi
Weiner, E.S.C., compiler
Clarendon Press, 1993
Buku Referensi
Peters, Pam
Cambridge University Press, 2006
Buku Referensi
Harper Collins Publishers, 2003
Buku Referensi