Nathan, N.M.L.
Macmillan Press , 1971
Buku Teks
Marshall, H.H.
Sweet & Maxwell Limited, 1959
Buku Teks
edited by Milton Fisk
Humanities Press, 1993
Buku Teks
Rawls, John, author
Harvard University Press, 2003
Buku Teks
Rawls, John, author
Harvard University Press, 2001
Buku Teks