Cieciuch, J. and Davidov, E. 2012. A comparison of the invariance properties of the PVQ-40 and the PVQ-21 to measure human values across German and Polish Samples. Survey Research Methods. 6, 1 (Apr. 2012), 37–48. DOI:https://doi.org/10.18148/srm/2012.v6i1.5091.