Due, John F., author
MIT Press, 1963
Buku Teks
Marcus, Edward, author
Bookman Associates, 1960
Buku Teks
Coughlan, Robert, author
Time Incorporated, 1962
Buku Teks
edited by John C. Caldwell and Chukuka Okonjo
Longmans, Green, 1968
Buku Teks
by William Brass ... [et al.]
Princenton University Press, 1968
Buku Teks