Llewellyn, Karl N.
Little, Brown and Company, 1960
Buku Teks
Postema, Gerald J.
Clarendon Press, 1986
Buku Teks
Holmes, Oliver Wendell, Jr.
Little, Brown and Company, 1951
Buku Teks
Eisenberg, Melvin A.
Harvard University Press, 1988
Buku Teks
Vinogradoff, Paul, 1854-1925
Oxford University Press, 1970
Buku Teks