sklearn.model_selection.StratifiedKFold, scikit-learn developers, 2023 - Official documentation for Scikit-learn's Stratified K-Fold cross-validator, detailing its parameters and usage.
An Introduction to Statistical Learning: With Applications in R, Gareth James, Daniela Witten, Trevor Hastie, Rob Tibshirani, 2021 (Springer) - A foundational textbook that explains the principles of cross-validation and model evaluation, relevant for understanding the theoretical basis of stratified k-fold.