Doran, Harold, Douglas Bates, Paul Bliese, and Maritza Dowling. “Estimating the Multilevel Rasch Model: With the Lme4 Package”. Journal of Statistical Software 20, no. 2 (February 22, 2007): 1–18. Accessed December 5, 2024. https://www.jstatsoft.org/index.php/jss/article/view/v020i02.