https://www.nytimes.com/2021/10/25/us/politics/russia-cybersurveillance-biden.html
https://jamestown.org/program/russias-cossacks-strategic-asset-or-financial-liability/
https://lansinginstitute.org/2021/10/12/russian-intelligence-focus-in-bulgaria/
https://www.kp.ru/daily/28335.5/4480309/
https://www.kp.ru/daily/28311.5/4452347/
https://www.kommersant.ru/doc/4919615