I think the main source may be in Russia; or that was with libgen.

But I could be wrong.

I am more surprised to see that there are so few alternatives to it. Or perhaps I am unaware of them but after Facebook and co declared war on libgen, and libgen going down, there were surprisingly few alternatives. Anna was one of the few. I still don't know what happened with libgen, but since the attack it really is kind of semi-gone.

Libgen and similar are more alive than ever with an extended botnet growing weekly. The "googlers" indexed framework is shrinking everyday, so users wont find it in those search engines easily, also it is hard to keep up with a good storage considering price trend last 5 years so the botnet and torrents are some kind of solution I guess. (We for instance are considering to use the old taping system, cause is at least a viable alternative.