Kaufman, Joyce P, author
Littlefield Publishers, 2013
Buku Teks
Lanyi, George A.
Random House , 1966
Buku Teks
McWilliams, Wayne C., author
Adamantine Press, 1990
Buku Teks
Carr, E.H. (Edward Hallet), author
Harver Torchbooks, 1947
Buku Teks
Knutsen, Torbjorn L.
Manchester University Press, 1992
Buku Teks