Schonlau, Matthias, Martin Reuter, Juergen Schupp, Christian Montag, Bernd Weber, Thomas Dohmen, Nico A. Siegel, Uwe Sunde, Gert G. Wagner, and Armin Falk. “Collecting Genetic Samples in Population Wide (Panel) Surveys: Feasibility, Nonresponse and Selectivity”. Survey Research Methods 4, no. 2 (September 11, 2010): 121-126. Accessed September 20, 2020. https://ojs.ub.uni-konstanz.de/srm/article/view/3959.