Hoffman, William H.
West Publishing, 1987
Buku Teks SO
Stephens, Richard B.
Warren, Gorham and Lamont, 1959
Buku Teks SO
Gaffney, Dennis J.
McGraw-Hill, 1984
Buku Teks
Burke, Karen C., 1951-
West Publishing, 1992
Buku Teks SO
Burke, Karen C., 1951-
West Publishing, 1996
Buku Teks SO