Five geometric origami books by Shuzo Fujimoto now public-domain: https://origami.kosmulski.org/blog/2022-10-23-fujimoto-books-public-domain, via https://news.ycombinator.com/item?id=33307845
They were originally published in the 1970s and 1980s and focus on polyhedra, tessellations, modular origami, and the like. In Japanese, but with lots of diagrams.