This is a topic where a big chunk of the highest-quality information is available only offline. A recent book has an entire chapter (22 pages) about the history of Brownie cameras:
Old Fields: Photography, Glamour, and Fantasy Landscape by John R. Stilgoe (2014), ISBN 978-0-8139-3515-7.
This has a side question: is there a business model for curated information about what ISN'T online (not even in Google Books)? I want a product that intercepts my Google web searches and tells me "You're wasting your time. Searches for this topic prove satisfactory in only 12% of cases. Consider buying some books or hiring an expert."