Asia-Europe Survey (ASES): https://www.icpsr.umich.edu/web/ICPSR/studies/22324
Candidate Countries Eurobarometer (CCEB): https://ec.europa.eu/commfrontoffice/publicopinion/archives/cceb2_en.htm
Consolidation of Democracy in Central and Eastern Europe (CDCEE): https://search.gesis.org/research_data/ZA4054
Eurobarometer (EB): https://ec.europa.eu/commfrontoffice/publicopinion
European Quality of Life Survey (EQLS): https://www.eurofound.europa.eu/surveys/european-quality-of-life-surveys
European Social Survey (ESS): https://www.europeansocialsurvey.org/
International Social Survey Programme (ISSP): http://www.issp.org/
Integrated and United: A Quest for a Citizenship in an Ever Closer Europe (INTUNE): https://www.mzes.uni-mannheim.de/d7/en/datasets/integrated-and-united-a-quest-for-a-citizenship-in-an-ever-closer-europe
Life in Transition Survey (LITS): https://www.ebrd.com/what-we-do/economic-research-and-data/data/lits.html
New Baltic Barometer (NBB): http://www.cspp.strath.ac.uk/catalog2_0.html
New Europe Barometer (NEB): http://www.cspp.strath.ac.uk/nebo.html
World Values Survey (WVS): http://www.worldvaluessurvey.org/wvs.jsp