Não informado. (1999). Shools in the middle. National Association of Secondary School Principals.
Chicago-viite (17. p.)Não informado. Shools in the Middle. Reston, Va: National Association of Secondary School Principals, 1999.
MLA-viite (8. p.)Não informado. Shools in the Middle. National Association of Secondary School Principals, 1999.
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