Sweet & Maxwell, 1984
Buku Teks
Redfern, Darren
Springer, 1998
Buku Teks
American Enterprise Institute for Public Policy Research, 1977
Buku Teks
Spencer, Donald D., author
Charles E. Merrill, 1982
Buku Teks SO
Orilia, Lawrence S., author
McGraw-Hill, 1982
Buku Teks SO