https://meduza.io/slides/pochemu-nuzhno-prochitat-solzhenitsyna-esli-vy-ego-esche-ne-chitali
http://www.rosbalt.ru/blogs/2018/11/27/1749250.html
https://www.kommersant.ru/doc/3812390
https://www.inopressa.ru/article/26Nov2018/dailybeast/spy.html
https://www.gazeta.ru/science/2018/11/26_a_12072121.shtml
http://expert.ru/2018/11/26/roskosmose_-ot-dyiryi-v-byudzhete-k-dyire-v-obshivke/
“Natural causes” can’t be ruled out. But those include stress, and there’s no doubt Gen. Korobov of the G(R)U was under a lot of that.
https://www.thedailybeast.com/inside-the-mystery-of-the-dead-russian-spy-chief
https://www.radiosvoboda.org/a/29617716.html