Depending on the type of book you need, libgen.is can be really useful
Piracy
Welcome to /c/piracy
No netflix or streaming services landlubbers allowed, this is pirates territory.
Libgen, scihub, and z-lib are some of the most important projects on the net today. They're our library of alexandria, and western publishers are doing their best to burn them down.
Z-Library is definitely what you need, but there’s still no dedicated community on Lemmy that I know of. You’ll find all that you need to access it in Reddit (r/zlibrary). Anna’s Archive is also very good, but sometimes the latest releases aren’t found there, while they are on Z-Lib
Anna's Archive is excellent. I use it as a backup in case Z lib is giving me problems.
Hav u guys checked /r/textbook (1st post has good links, pls ppl share too)
I would like to recommend this page (a good collection of PDF textbooks) - Ultimate Guide to Downloading Free PDF Textbooks
VK has many pages dedicated to this. Here are a few:
https://vk.com/engbooksandmags
Try IRC bots
Oh man, the #audiobookz and #ebooks channel on IRC were awesome!! got my first taste of books from there
libgen, zlibrary, annas archive all of them are good and have books in PDF format but if you don't mind me asking, what's wrong with EPUB ?
There's nothing wrong with epub, but there are lots of non-fiction books that have images, tables, and so on, I believe it's impossible to convert such books into epub or something like that. Also there are tons of books that were digitally published in pdf, and they also need to be pirated.
I don't think it's impossible to convert them to epub, iirc epub is actually Turing complete. But it doesn't make much sense to convert your carefully typeset/layed out PDF to a format whose entire point is that the typesetting and layout is dynamic and taken care of by your device.