You can also check Z-library. If you can't find what you are looking for and you know that an ebook version exists I may be able to get a copy of it, feel free to mail me (see address and GPG key on my profile).
Also know that the website is currently unstable due to ongoing technical improvements. So if you can't reach it you should try again later.
I have some good PDF ebooks I'm willing to share, but I suspect the seller embeds some tracking data in them to link them to my account, as every time I download them from the official website they have a different hash while being visually identical. The same when checking against the copies a friend bought from the same seller. Since I dont wanna get banned, can you recommend a way to remove that stuff?