Não informado. (1926). Bulletin of the National Association of Secondary School Principals. National Association of Secondary School Principals.
Chicago-referens (17:e uppl.)Não informado. Bulletin of the National Association of Secondary School Principals. Washington: National Association of Secondary School Principals, 1926.
MLA-referens (8:e uppl.)Não informado. Bulletin of the National Association of Secondary School Principals. National Association of Secondary School Principals, 1926.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.