Stevenson, Adlai E., author
Harper & Row, 1961
Buku Teks
Thomson, Charles A.
Indiana University Press, 1963
Buku Teks
Holt, Robert T., author
University of Chicago Press, 1960
Buku Teks
edited by M.G. Mori
J.L. Thompson, 1937
Buku Teks
Douglas, William O., author
Princeton University Press, 1960
Buku Teks