Hin, Lin Yee, and Vincent Carey. “An Algorithm for Clustered Data Generalized Additive Modelling With S-PLUS”. Journal of Statistical Software 14, no. 8 (August 31, 2005): 1–24. Accessed November 21, 2024. https://www.jstatsoft.org/index.php/jss/article/view/v014i08.