McIlroy, John
Manchester University Press , 1995
Buku Teks
Laski, Harold J.
George Allen and Unwin, 1960
Buku Teks
Rees, Albert
University of Chicago Press, 1962
Buku Teks
Kilian, Michael
st Matins, 1982
Buku Teks
Barbash, Jack
John Hopkins Press, 1972
Buku Teks