https://wiiw.ac.at/regulatory-convergence-within-technical-barriers-to-trade-dlp-6630.pdf
https://trade.ec.europa.eu/doclib/docs/2018/april/tradoc_156791.pdf
https://www.lobbycontrol.de/wp-content/uploads/gaslobby-studie-lobbycontrol.pdf
https://www.piie.com/sites/default/files/documents/wp22-12.pdf