Não informado. (2008). School bell. National School Public Relations Association.
Chicago-referens (17:e uppl.)Não informado. School Bell. Washington: National School Public Relations Association, 2008.
MLA-referens (8:e uppl.)Não informado. School Bell. National School Public Relations Association, 2008.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.