Curzon, L.B.
Pitman, 1994
Buku Referensi
editor, Elizabeth A. Martin
Oxford University Press, 1994
Buku Referensi
Oxford University Press, 2009
Buku Referensi
Bird, Roger
Sweet & Maxwell, 1983
Buku Teks
Oran, Daniel
West Publishing Co., 1975
Buku Teks