A Harvard scientist has been accepting cash from the energy industry, namely the Koch brothers, in order to push junk science that claims to refute man-made climate change, reported The New York Times. This is the most recent case of Koch-purchased science, but it’s hardly the first.

In the past, the Koch brothers “have donated at least $67 million to organizations that blast out disinformation relating to climate change,” reported Addicting Info.

Below, in its entirety, is the documentary The Koch Brothers Exposed. The film sheds light on the Koch-money network and how it influences scientific studies on climate change.