1. 1. Cyber defence. NATO. URL: https://www.nato.int/cps/en/natohq/topics_78170.html
2. 2. Cyberwar timeline. InfoPlease. URL: https://www.infoplease.com/world/cyberwar-timeline#1980
3. 3. 30 years ago, the world's first cyberattack set the stage for modern cybersecurity challenges. The Conversation. URL: https://theconversation.com/30-years-ago-the-worlds-first-cyberattack-set-the-stage-for-modern-cybersecurity-challenges-105449
4. 4. The Age of Cyberwarfare. Columbia Magazine. URL: https://magazine.columbia.edu/ rticle/age-cyberwarfare
5. 5. Kaiser R. The birth of cyberwar. Political Geography. 2015, Vol. 46, pp. 11-20. URL: https://doi.org/10.1016/j.polgeo.2014.10.001