1. Tor project.
https://github.com/torproject/tor
2. Skynet, a Tor-powered botnet straight from Reddit (2012).
https://community.rapid7.com/community/infosec/blog/2012/12/06/skynet-a-tor-powered-botnet-straight-from-reddit
3. Austrian Tor exit node operator found guilty as an accomplice because someone used his node to commit a crime (2014).
https://www.techdirt.com/articles/20140701/18013327753/tor-nodes-declared-illegal-austria.shtml
4. Back, A., Möller, U., Stiglic, A.: Traffic analysis attacks and trade-offs in anonymity providing systems. In: 4th International Workshop on Information Hiding (IH), pp. 245–257 (2001)
5. Lecture Notes in Computer Science;DJ Bernstein,2006