David A Johnstonの動画集。https://medium.com/@DJohnstonEC/videos-of-david-johnston-talking-about-bitcoin-the-blockchain-ca3ebd6d5309 rivetz。https://www.youtube.com/watch?v=AAXrX91ZPVM#t=33m Nxt。http://cointelegraph.com/news/113223/the-nx…