Wagner, M., G. Franzmann, and J. Stauder. “Neue Befunde Zur Pluralität Der Lebensformen: New Results on the Plurality of Living Arrangements”. Journal of Family Research, vol. 13, no. 3, Dec. 2001, pp. p. 52-73, https://ubp.uni-bamberg.de/jfr/index.php/jfr/article/view/482.