1. Moscow Times. "Inside Russia's Top Secret 'F' Underground Aerospace Defense Base".:(https://www.themoscowtimes.com/2015/01/28/inside-russias-top-secret-f-underground-aerospace-defense-base-a43337)
2. BBC News. "Inside the secret network protecting Britain from cyber attacks".:(https://www.bbc.com/news/uk-50083026)
3. Popular Mechanics. "Russia's Mysterious F-16: Could It Be A New Electronic Warfare Jet for Putin's Air Force?".:(https://www.popularmechanics.com/military/aviation/a27892395/russia-f-16-ew/)