http://sverigesradio.se/sida/artikel.aspx?programid=2103&artikel=6154055
http://www.vedomosti.ru/opinion/articles/2015/04/30/sakralnaya-sluzhba-rossiiskoi-federatsii
http://qz.com/394625/russias-gas-weapon-gazprom-is-rapidly-losing-pressure/
http://ru.reuters.com/article/businessNews/idRUKBN0NK17020150429