Heise-Echelon Archiv: http://www.heise.de/tp/deutsch/special/ech
Interception Capabilities 2000, STOA Report 1999, Duncan Campbell
``Somebody's Listening'', Duncan Campbell
Federation of American Scientists, http://www.fas.org
Report on Carnivore Diagnostic Tool - http://www.fbi.gov/pressrm/congress/congress00/
``Secret Power'', Nicky Hager, 1996
NSA Wordspotting, http://jya.com/nsa-word.htm
Vortrag ``Inside Echelon'', Duncan Campbell, 16C3 1999