Spinello, Richard A., author
Jones and Bartlett Learning, 2017
Buku Teks
Hart, H.L.A., author
Standford University Press, 1969
Buku Teks
Raz, Joseph, author
Oxford Univesity Press, 2009
Buku Teks
Raz, Joseph, author
Clarendon Press, 1979
Buku Teks
Mitchell, Basil, author
Oxford University Press, 1970
Buku Teks