https://lansinginstitute.org/2021/10/12/russian-intelligence-focus-in-bulgaria/
https://www.ng.ru/ng_energiya/2021-10-11/9_8274_infrastructure.html
https://analytics.hvylya.net/239257-zelenskiy-speshit-uvidet-putina-kakimi-mogut-byt-posledstviya
https://jamestown.org/program/the-realities-of-russian-military-shipbuilding-part-one/
https://www.rbc.ru/newspaper/2021/10/04/61571a279a79478e0bc0b011