http://thinkprogress.org/climate/2016/04/14/3769380/exxon-ad-melt-glaciers/
"Newly-released oil industry documents push back the start date of the world’s most successful disinformation campaign to the 1960s, if not earlier. The must-read documents, published by The Center for International Environmental Law (CIEL), strengthen the hand of the numerous attorneys general investigating whether ExxonMobil engaged in a cover-up to mislead the public and investors about the dangers of human-caused climate change."
