National Association of Secondary School Principals (U.S.). (1981). Schools in the middle. The Association.
Citazione stile Chigago Style (17a edizione)National Association of Secondary School Principals (U.S.). Schools in the Middle. Reston, Va.: The Association, 1981.
Citatione MLA (9a ed.)National Association of Secondary School Principals (U.S.). Schools in the Middle. The Association, 1981.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.