Laski, Harold J., author
George Allen and Unwin, 1960
Buku Teks
Harper and Brothers, 1959
Buku Teks
McIlroy, John, author
Manchester University Press , 1995
Buku Teks
Rees, Albert, author
University of Chicago Press, 1962
Buku Teks
Crawford, R. M.
Hutchinson's University Library, 1955
Buku Teks