Ryan, William
Learning System of Company, 1971
Buku Teks
Ryan, William T.
Dew Jones Irwin, 1980
Buku Teks
Dwyer, F. Robert, author
McGraw-Hill, 2002
Buku Teks
Dwyer, F. Robert, author
McGraw-Hill, 2009
Buku Teks
Kurtz, David L., author
The Dryden Press , 1981
Buku Teks