"De architectura (Ten Books on Architecture)". Book by Marcus Vitruvius Pollio (Book II, Chapter X "Highland and Lowland Fir", Section 1), circa 15 BC.
"THE BILL GATES INTERVIEW: An energy miracle is coming, and it's going to change the world". Interview with Drake Baer, www.businessinsider.com. February 22, 2016.
"Global Warming and the Future of Humanity: An Interview With Noam Chomsky and Graciela Chichilnisky". Interview with C.J. Polychroniou, truthout.org. September 17, 2016.