Não informado. (2008). School bell. National School Public Relations Association.
Chicago-Zitierstil (17. Ausg.)Não informado. School Bell. Washington: National School Public Relations Association, 2008.
MLA-Zitierstil (8. Ausg.)Não informado. School Bell. National School Public Relations Association, 2008.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.