Wallace, Iain
Routledge , 1990
Buku Teks
Williams, Marc
Harvester Wheatsheaf , 1994
Buku Teks
Weiss, John, author
Prentice-Hall, 1995
Buku Teks
Mason, Edward S., author
Fordham University Press, 1958
Buku Teks
Bunn, Isabella D., author
Hart Publishing, 2012
Buku Teks