Aberdeen University Press , 1990
Buku Teks
Paul, Pamela, author
Random House, 2003
Buku Teks
Moule, Terry
Kyle Cathie , 2000
Buku Teks
Butler, George D.
McGraw-Hill Book Company, Inc., 1949
Buku Teks
Butler, William J.
International Commission of Jurists, 1977
Buku Teks