Não informado. Educators guide to free filmstrips. Educators Progress Service.
Chicago-referens (17:e uppl.)Não informado. Educators Guide to Free Filmstrips. Randolph, Wis: Educators Progress Service.
MLA-referens (8:e uppl.)Não informado. Educators Guide to Free Filmstrips. Educators Progress Service.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.