Reddit reviews The Tragedy of Cambodian History

What, a source for the Khmer Rouge being put into power with the help of the Vietcong by overthrowing an American regime? I didn't realise that was up for debate, seems to me to be a simple matter of historical fact. I shouldn't need to cite sources for that any more than I'd need to cite sources if I claimed that the USA invaded Vietnam or the French Revolution occurred. I'm not writing a thesis, here.

Wikipedia lists many sources on the page for the Cambodian Civil War, try checking those out, but you might start with this, this, this or this. While we're at it, here's a page linking to several Guardian articles from the period concerning the Khmer Rouge, and here, here and here are articles from three different anti-genocide organisations, all of which describe the Khmer Rouge overthrowing an American-backed government.