I recently found a collection of French photo magazines from the 1920s and 1930s on eBay. I thought it would be fun to see how people experienced photography at the time. The collection contains two editions of La Photo Pour Tous. This magazine was published by Henri Plait of Photo-Plait.
I found a catalog from 1918 by Photo-Plait from Paris. This photography store sold stereoviews of the First World War. To my surprise, the numbers in the catalogue correspond to the numbers on the slides of La Stéréoscopie Universelle. It establishes the link between producer and seller.