WWII radio coil technical booklet w/photos, National Radio Institute

Old 1937 (this is a 1940 edition) booklet on the technology of radio coils and how they work. This booklet is published by the National Radio Institute.

This has 29 pages with drawings, schematics, and photos, including some interesting photos of the equipment in the factory making radio coils

This has wear and some soil and as it turns out, someone has snipped up one of the pages for some of the illustrations (please see the third photo).