XGBoost: A Scalable Tree Boosting System, Tianqi Chen and Carlos Guestrin, 2016Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining (ACM)DOI: 10.1145/2939672.2939785 - Details the regularized objective function, second-order Taylor approximation, and L1/L2 penalties as implemented in XGBoost.
Greedy Function Approximation: A Gradient Boosting Machine, Jerome H. Friedman, 2001Annals of Statistics, Vol. 29 (Institute of Mathematical Statistics) - Introduces the foundational gradient boosting machine algorithm, which forms the basis for modern gradient boosting frameworks and their objective function minimization.
XGBoost Parameters, XGBoost Contributors, 2023 - Official documentation explaining the reg_alpha (L1) and reg_lambda (L2) parameters and their role in regularizing XGBoost models.