Não informado. (2002). Principal Leadership. National Association of Secondary School Principals.
Chicago-referens (17:e uppl.)Não informado. Principal Leadership. Reston, Va: National Association of Secondary School Principals, 2002.
MLA-referens (8:e uppl.)Não informado. Principal Leadership. National Association of Secondary School Principals, 2002.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.