Sage, 1981
Buku Teks
Llewellyn, Karl N.
Little, Brown and Company, 1960
Buku Teks
Cooper, Phillip J.
Oxford University Press , 1988
Buku Teks
Chamberlain, Joseph P.
Books for Libraries Press , 1942
Buku Teks
Medina, Harold R.
Matthew Bender, 1954
Buku Teks