Kraus, Michael, author
University of Oklahoma Press, 1953
Buku Teks
Hofstadler, Richard
Prentice-Hall, 1895
Buku Teks
Arnot, Dorothy S.
Macmillan, 1962
Buku Teks
Angle, Paul M.
Rand McNally , 1958
Buku Teks
Morison, Samuel Eliot, author
Oxford University Press, 1962
Buku Teks