D. Stiers, M. Hooghe, C. De Grauwe, and A. Voets, “Online Answers to a Postal Survey: A Comparison of Election Surveys in Belgium, 2019-2024”, SRM, vol. 20, no. 2, pp. 219–228, Aug. 2026, doi: 10.18148/srm/2026.v20i2.8504.