Where can you find vis-o-draft manual 1930s or 1940s - beer dispenser?

I am unable to locate any information about a "vis-o-draft manual" related to a beer dispenser. It's possible that the item or term you're referring to may have a different name or was a regional product not widely known. Are you sure about the name and the purpose of the item? Providing more accurate or alternative details might help in further research.