Bettany, G.T.
Bracken Books, [date of publication not identified]
Buku Referensi
edited by Stewart Sutherland, Leslie Houlden, Peter Clarke, Friedhelm Hardy
Routledge, 1988
Buku Referensi
James Fieser, John Powers, editors
McGraw-Hill, 2012
Buku Teks
editor, John R. Hinnells
Macmillan, 1993
Buku Referensi
edited by Peter Clarke
Routledge, 1990
Buku Teks