Não informado. (1989). Adults Learning. National Institute of Adult Continuing Education.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Adults Learning. Leicester, Inglaterra: National Institute of Adult Continuing Education, 1989.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Adults Learning. National Institute of Adult Continuing Education, 1989.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.