Stemmler, Mark, Jörg-Henrik Heine, and Susanne Wallner. “Person-Centered Data Analysis With Covariates and the R-Package Confreq”. Methodology 17, no. 2 (June 30, 2021): 149-167. Accessed September 22, 2021. https://meth.psychopen.eu/index.php/meth/article/view/2865.