Touloumis, Anestis. “R Package Multgee: A Generalized Estimating Equations Solver for Multinomial Responses”. Journal of Statistical Software 64, no. 8 (March 20, 2015): 1–14. Accessed June 30, 2024. https://www.jstatsoft.org/index.php/jss/article/view/v064i08.