Which reminds me: Does anyone perchance know an online source for French topographical maps from the first half of the 20th century? I still need to add the secondary lines to the #RailwayHistoryMap but quite a few are already missing on the 1950s maps that IGN has.
Edited to add: In order to be able to trace the lines, the scale needs to be at least 1:100,000 but something like 1:50,000 or even better would be great.
