De Smith, S.A. (Stanley A.), author
Penguin Education, 1973
Buku Teks
Thompson, Brian
Blackstone press , 1997
Buku Teks
Robson, William Alexander, 1895-1980, author
Stevens & Sons Limited, 1951
Buku Teks
Marston, John
Pitman, 1993
Buku Teks
Barendt, E. M., author
Oxford University Press, 1998
Buku Teks