Stanford, David R.
London, Sweet & Maxwell Limited
Buku Teks
Waddington, P.A.J
Avebury, 1993
Buku Teks
Mortimer, J.E.
Oxford University Press , 1971
Buku Teks
Clegg, H. A., author
Clarendon Press, 1964
Buku Teks
Kirkman, Patrick R. A.
George Allen and Unwin, 1977
Buku Teks