Belliotti, Raymond A., author
Wiley-Blackwell, 2014
Buku Teks
Kamm, F.M.
Oxford University Press, 1992
Buku Teks
Selekman, Benjamin M.
New York, N.Y., McGraw-Hill Book Company
Buku Teks
Kelsen, Hans, author
Alumni, 1982
Buku Teks
edited by Carl J. Friedrich
The Modern Library, 1949
Buku Teks