1. Bosse, G., Schmidt-Felzmann, A. (2011). The Geopolitics of Energy Supply in the ‘Wider Europe’. Geopolitics, 16(3), 479-485.10.1080/14650045.2011.520854
2. Dickel R., Hassanzadeh E., Henderson J. et al. (2014). Reducing European Dependence on Russian Gas: distinguishing natural gas security from geopolitics. OIES Paper: No NG 92.
3. European Commission (2015). Energy Union Package. Retrieved from https://eurlex.europa.eu/resource.html?uri=cellar:1bd46c90-bdd4-11e4-bbe1-01aa75ed71a1.0001.03/DOC_1&format=PDF.
4. European Commission. (2022). Database – Eurostat. Retrieved from https://ec.europa.eu/eurostat/databrowser/explore/all/all_themes?lang=en&display=list&sort=category.
5. European Council. EU restrictive measures in response to the crisis in Ukraine. Retrieved from https://www.consilium.europa.eu/en/policies/sanctions/ukraine-crisis/.