Gerston, Larry N.
Scott Foresman and Company, 1983
Buku Teks
Peters, B. Guy, author
Sage , 2013
Buku Teks
Manley, John F., author
Macmillan, 1976
Buku Teks
by James W. Ceaser ... [and others]
McGraw-Hill , 1984
Buku Teks
Kennedy, John F.
Harper & Row Pub., 1964
Buku Teks