Chatam House, 1984
Buku Teks
Lipson, Leslie, author
Prentice-Hall, 1965
Buku Teks
Sederberg, Peter C.
Chandler & Sharp Publishers, 1977
Buku Teks
Rush, Michael, author
Harvester Wheatsheaf, 1992
Buku Teks
Roelofs, H. Mark
The Dorsey press, 1968
Buku Teks