https://glavcom.ua/economics/finances/trivoga-u-peredchutti-gazovogo-miru-649370.html
https://www.gazeta.ru/business/2019/12/25/12883622.shtml
https://www.rbc.ru/newspaper/2019/12/24/5e00b8829a794766b4206502
http://www.ng.ru/cis/2019-12-24/5_7760_ukraine.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
http://www.ng.ru/cis/2019-12-23/5_7759_ukraine.html
https://www.kommersant.ru/doc/4205887