https://www.rosbalt.ru/blogs/2019/12/24/1820176.html
SOFIA, Bulgaria -- The Russian assassin used an alias, Sergei Fedotov, and slipped into Bulgaria unnoticed, checking into a hotel in Sofia near the office of a local arms manufacturer who had been selling ammunition to Ukraine.He led a team of three men.Within days, one man sneaked into a locked parking
https://news.yahoo.com/poisoning-bulgaria-exposed-russian-assassins-133100185.html
https://www.inopressa.ru/article/23Dec2019/nytimes/gebrev.html
http://www.ng.ru/blogs/filatov/byl-li-evgeniy-manyurov-poleznym-idiotom-.php
http://www.ng.ru/politics/2019-12-23/100_echo23122019.html
https://www.nytimes.com/2019/12/22/world/europe/bulgaria-russia-assassination-squad.html
https://zn.ua/internal/polzuchaya-amnistiya-340054_.html
https://lenta.ru/articles/2019/12/21/bunt/