https://www.washingtonpost.com/news/wonk/wp/2016/02/16/its-time-to-kill-the-100-bill/ http://www.hks.harvard.edu/content/download/79140/1776759/version/1/file/Eliminating+HDNfinalXYZ.pdf https://www.reddit.com/r/btc/comments/462v8u/andreasmantonopoulos_on_twitter_government_say/ https://twitter.com/aantonop/status/699610460279197697