https://www.theguardian.com/commentisfree/2018/sep/06/google-search-results-rigged-news-donald-trump

Treating search results as a media source in their own right is a key step in analyzing alleged political bias

Since Donald Trump announced his presidential run in 2016, his list of adversaries seems to grow endlessly, from career politicians to celebrities to media outlets. But this past Tuesday, that list saw an unusual addition: Google. Trump angrily touted on Twitter that the dominant search engine had “RIGGED” its search results by shutting out rightwing media and directing users to content from “Fake News” leftwing media. But behind the bombast, does he have a point? Are search engine results biased? And if they were, how would we know?