MacLearly, Alistar R.
E. & F.N. Spon, 1991
Buku Teks
Megarry, Robert, author
Stevens and Sons, 1975.
Buku Teks
Lawler, J. John, author
Foundation Press, 1940
Buku Teks
Simpson, A.W.B., author
Clarendon Press, 1986
Buku Teks
Morgan, David R. (David Reginald), 1946-, editor
The Institute of Economic Affairs , 1977
Buku Teks