1. Andrew C, Gordievsky O (1990) KGB: The inside story of its foreign operations from Lenin to Gorbachev. HarperCollins, New York, NY
2. Andrew C, Mitrokhin V (1999) The Sword and the shield: The mitrokhin archive and the secret history of the KGB. Basic Books, New York, NY
3. Aro J (2015) My year as a Pro-Russian Troll Magnet. YLE Kioski, 30. Available at:
http://kioski.yle.fi/omat/my-year-as-a-pro-russia-troll-magnet
4. Ashley R (2018) Testimony before the Senate, 6 March. Available at:
http://www.dia.mil/News/Speeches-and-Testimonies/Article-View/Article/1457815/statement-for-the-record-.worldwide-threat-assessment/
5. Barkanov B (2018) Natural gas. In: Tsygankov AP (ed.) Routledge handbook of Russian foreign policy. Routledge, Abingdon, pp 138–152