Davis, F.T.
Institute for Business Planning, 1981
Buku Teks
Weideman, Hugh
Thomas Y. Crowell Company, 1958
Buku Referensi
Jones, Leo
Cambridge University Press, 1989
Buku Teks
Seoul Gemseong Chulpansa, 1999
Buku Referensi
editors, Gerald P. Koocher, John C. Norcross, Sam S. Hill, III
Oxford University Press, 2005
Buku Teks