Wesley-Smith, Peter, author
Oxford University Press, 1987
Buku Teks
Wrightsman, Lawrence S., author
Brooks/Cole , 1998
Buku Teks
Danner
Buku Teks
Foster, Nigel G., author
Blakcstone Press, 1993
Buku Teks
Howarth, David A.
Blackstone Press, 1992
Buku Teks