Dear Gusti:

See this News Tracer tool developed by Reuters. According to Columbia Journalist Review, it "analyzes every tweet in real time—all 500 million or so each day" , and "assigns a credibility score based on the sorts of factors a human would look at, including the location and identity of the original poster, whether he or she is a verified user, how the tweet is propagating through the social network, and whether other people are confirming or denying the information. Crucially, Tracer checks tweets against an internal “knowledge base” of reliable sources. Here, human judgment combines with algorithmic intelligence: Reporters handpick trusted seed accounts, and the computer analyzes who they follow and retweet to find related accounts that might also be reliable."

Perhaps it will be also useful the paper about how to identify bots on twitter.

https://www.cjr.org/analysis/cyborg_virtual_reality_reuters_tracer.php

This article might be helpful as well: 

http://onlinelibrary.wiley.com/doi/10.1002/pra2.2015.145052010082/full

Do you know about the fact checking site Snopes? Here is the link-

http://www.snopes.com