As the years are passing, the search engines are becoming each more dreadful to use. Sometimes, the best is to go direct on some site that hold a big base of knowledge.
Books:
- WikiSource: A big selection of books
- InternetArchive: Its a gigantic media library, you can found any kind of media on this… from android apks to old newspapers from 1800s.
- Slum : The Shadow Library Uptime Monitor: Its a dashboard that tracks the availability of popular shadow libraries