Schwinn provided a great deal of documentation with and about their bikes.
In fact from 1895 on, their was a yearly catalog.
Most bikes sold came with documentation like user manuals. Dealers received special documentation listing specifications, part numbers, accessories, etc.
The majority of this site uses Schwinn documentation as a source of information. In particular, I have used the consumer catalogs that Schwinn published every year as a source of images and information to help collectors and enthusiasts learn more about their bikes.
Schwinn Owners Manuals
Schwinn Dealer Catalogs