Não informado. (1915). Accident prevention magazine. Portland Cement Association.
Chicago-referens (17:e uppl.)Não informado. Accident Prevention Magazine. Chicago, Ill: Portland Cement Association, 1915.
MLA-referens (8:e uppl.)Não informado. Accident Prevention Magazine. Portland Cement Association, 1915.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.