http://stateofthenation2012.com/?p=70078 (Alan Standorf)
https://www.mcall.com/news/mc-xpm-1991-02-07-2786588-story.html (Alan Standorf)
https://www.washingtonpost.com/graphics/2020/world/national-security/cia-crypto-encryption-machines-espionage/ (Boris Hagelin Sr)
http://users.telenet.be/d.rijmenants/en/hagelin.htm (Boris Hagelin Sr.)
