Não informado. (1980). Principal. National Association of Elementary School Principals.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Principal. Arlington, Va: National Association of Elementary School Principals, 1980.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Principal. National Association of Elementary School Principals, 1980.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.