1. Yōzu (Kūchū shashin sokuryō) Kita Shina jūmanbun no ichi zu, Maps Index
1940. Stanford Geospatial Center. This polygon shapefile is an index to 1:100,000 scale topographic maps of Northern China, titled 'Yōzu (Kūchū shashin sokuryō) Kita Shina jūmanbun ... Stanford Digital Repository.