https://www.radiosvoboda.org/a/rosija-pvk-vagner/29609280.html
https://zn.ua/international/afganskoe-pole-dlya-igr-kremlya-300460_.html
https://republic.ru/posts/92432
Early in the morning, just before nine o’clock, a young man in a blue hooded coat arrived at the entrance of the security agency (FSB) office in Archangelsk, in Russia’s Far North. He took a device out of his small rucksack. A second later, an explosion ripped through the entranceway. The young man was left dead. Three security officers, who had arrived for the start of the working day, were seriously injured by shrapnel.
http://www.kasparov.ru/material.php?id=5BDAA2E98E813