Não informado. (1948). Language Learning. Research Club in Language Learning.
Chicago-referens (17:e uppl.)Não informado. Language Learning. Ann Arbor, Mich: Research Club in Language Learning, 1948.
MLA-referens (8:e uppl.)Não informado. Language Learning. Research Club in Language Learning, 1948.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.