https://tyzhden.ua/%D0%A1%D0%B2%D1%96%D1%82/253450
https://www.nytimes.com/2021/10/25/us/politics/russia-cybersurveillance-biden.html
https://carnegie.ru/commentary/85483
https://lansinginstitute.org/2021/10/12/russian-intelligence-focus-in-bulgaria/
https://www.rosbalt.ru/blogs/2021/10/07/1924690.html
http://region.expert/landscape/