O`Connell, Jeffrey
Commerce Clearing House, 1971
Buku Teks
edited by William F. Bluhm, Daniel D. Skwire, Stephen J. Kaczmarek and Kristi M. Bohn
ACTEX Publications, 2012
Buku Teks
Munch, James C.
Little, Brown and Company, 1981
Buku Teks
Keeton, Robert E.
West Pub. Co., 1960
Buku Teks
Keeton, Robert E.
West Publishing, 1988
Buku Teks