Não informado. (1999). Shools in the middle. National Association of Secondary School Principals.
Chicago-Zitierstil (17. Ausg.)Não informado. Shools in the Middle. Reston, Va: National Association of Secondary School Principals, 1999.
MLA-Zitierstil (8. Ausg.)Não informado. Shools in the Middle. National Association of Secondary School Principals, 1999.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.