Hutton, Christopher, author
Routledge, 1998
Buku Teks
Deakin, F. W.
Harper-Raw, 1962
Buku Teks
Koob, Derry D., author
Addison-Wesley, 1971
Buku Teks
Baldwin, Ernest, author
University Press, 1962
Buku Teks
Marwick, Arthur
London MacMillan 1992
Buku Teks