Fox, Harold W.
Public Affairs Press, 1968
Buku Teks
Fox, Michael W.
University Park Press, 1983
Buku Teks
Fox, Harrison W.
The Free Press, 1977
Buku Teks
Metz, Harold W.
The Brookings Institution, 1945
Buku Teks
Gingrich, Harold W.
Prentice-Hall, 1979
Buku Teks