@Satsuma Cambridge Uni have just put up a lot of textbooks free online - only until May, and in html format, mostly a chapter at a time rather than the full book. https://www.cambridge.org/core/what-we-publish/books
The Wandering Shop is a Mastodon instance initially geared for the science fiction and fantasy community but open to anyone. We want our 'local' timeline to have the feel of a coffee shop at a good convention: tables full of friendly conversation on a wide variety of topics. We welcome everyone who wants to participate, so long as you're willing to abide by our code of conduct.