https://nv.ua/opinion/zubov/schastlivyj-den-putina--2470039.html
http://www.kasparov.ru/material.php?id=5AFBC4418C668
http://www.rosbalt.ru/world/2018/05/16/1703554.html
https://carnegie.ru/commentary/76364
http://www.rosbalt.ru/russia/2018/05/16/1703536.html
https://www.rbc.ru/newspaper/2018/05/16/5afb202e9a79474bb9eb247e
https://www.kommersant.ru/doc/3629459
https://www.kommersant.ru/doc/3629475
https://www.rbc.ru/newspaper/2018/05/16/5afad1ab9a79472c8aaae1b1
The crash of a Polish Air Force Tu-154 airliner near the Russian city of Smolensk on April 10, 2010 killed Polish President Lech Kaczyński and his wife.
http://observer.com/2018/05/evidence-shows-russia-had-role-in-smolensk-crash-killed-kaczynski/