Maizell, Robert E., author
John Wiley & Sons, 1979
Buku Referensi
Bouscaren, Anthony Trawick
Henry Regnery Company, 1958
Buku Teks
Day, Ralph L.
Richard D. Irwin, 1962
Buku Teks
Feith, Herbert
Yale University , 1987
Buku Teks
edited by Colin Cameron
Sage, 2014
Buku Teks