I've been searching this forum for the same post, and don't find one so I post it here (sorry if there's a similar post that I failed to see ). The link is :
_http://www.mcu.cz/atm/index.php
This is a free registration server, so just register using the login button in the top right of the page before downloading. It contains, quite a lot of ebooks, hardware specs, and the likes, it's mostly related to electrical engineering, software engineering and telecommunication engineering. There are other stuff though. Just check it out .