Não informado. (1989). Adults Learning. National Institute of Adult Continuing Education.
Chicago-referens (17:e uppl.)Não informado. Adults Learning. Leicester, Inglaterra: National Institute of Adult Continuing Education, 1989.
MLA-referens (8:e uppl.)Não informado. Adults Learning. National Institute of Adult Continuing Education, 1989.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.