Spragens, William C
University Press of America, 1979
Buku Teks
Strober, Gerald S., author
Harper Perennial, 1994
Buku Teks
Jugoslovenski pregled , 1979
Buku Teks
Catanach, I.J.
University of California Press, 1970
Buku Teks
Nash, Bradley D
Center for the study of the Presidency, 1980
Buku Teks