The wikipedia article has over 600 hundred references, including a section specifically on the disinformation campaign.

Russian use of social media to disseminate propaganda content was very broad. Facebook and Twitter were used, but also Reddit, Tumblr, Pinterest, Medium, YouTube, Vine, and Google+ (among other sites). Instagram was by far the most used platform, and one that largely remained out of the public eye until late 2018.

Advertisements bought … are estimated to have reached 10 million users. But many more Facebook users were contacted by accounts created by Russian actors. 470 Facebook accounts are known to have been created by Russians … Of those accounts six generated content that was shared at least 340 million times, … The most strident Internet promoters of Trump were paid Russian propagandists/trolls, …

In continued analysis … researchers found the most prominent methods of misinformation were ostensibly “organic posting, not advertisements”

Facebook originally denied that fake news on their platform had influenced the election and had insisted it was unaware of any Russian-financed advertisements but later admitted that about 126 million Americans may have seen posts published by Russia-based operatives.

There is more, but I think the 600+ sources in the wikipedia article do a better job than I ever will.