Gillen, T. (1992). Assertiveness for managers. Gower.
Chicago Style aipamenaGillen, Terry. Assertiveness for Managers. Aldershot, Hants: Gower, 1992.
MLA aipamenaGillen, Terry. Assertiveness for Managers. Gower, 1992.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.