Swan, Michael
Oxford University Press, 1995
Buku Teks SO
Weiner, E.S.C., compiler
Clarendon Press, 1993
Buku Referensi
Fowler, H.W. [Henry Watson], 1858-1933
New York Oxford University Press 1965
Buku Referensi
Peters, Pam
Cambridge University Press, 2006
Buku Referensi
Stone, Linton
Macmillan, 1970
Buku Teks SO