Elliot, Florence
Penguin Books, 1957
Buku Referensi
McCarthy, Eugene J., 1916-2005
Macmillan, 1962
Buku Teks SO
edited by Edward Conrad Smith and Arnold John Zurcher
Barnes & Noble, 1966
Buku Teks SO
Comfort, Nicholas
Cassell Publishers, 1993
Buku Referensi
Collin, P. H.
Peter Collin Publishing, 1997
Buku Referensi