https://www.rbc.ru/newspaper/2021/12/06/61aa3c879a7947e608b37485
https://www.nytimes.com/2021/12/05/world/europe/putin-russia-ukraine-troops.html
https://nvo.ng.ru/realty/2021-12-02/1_1168_east.html
https://www.bbc.com/russian/news-59491511
https://www.kommersant.ru/doc/5100564