Andrews, William D., 1931-
Aspen Law & Business, 1973
Buku Teks SO
Gaa, Charles J.
McGraw-Hill , 1965
Buku Referensi
Gaa, Charles J.
McGraw-Hill , 1965
Buku Referensi
Dodge, Joseph M., 1941-
Michie, 1995
Buku Teks SO
Williamson, J. Peter (John Peter)
Scott, Foresman, 1968
Buku Teks SO