Dubois, Brenda, 1949-, author
Allyn and Boston, 1992
Buku Teks
Gore, M.S., author
Asia Publishing House, 1965
Buku Teks
T. Daniel Coggin, Frank J. Fabozzi, editors
Frank J. Fabozzi Associates, 1997
Buku Referensi
Cohen, Nathan Edward, author
National Ass. of Workker, 1964
Buku Teks
Goleman, Daniel, author
Bantam Dell, 2006
Buku Teks