An Introduction to Statistical Learning with Applications in R, Gareth James, Daniela Witten, Trevor Hastie, Robert Tibshirani, 2013 (Springer) - A fundamental textbook that provides an accessible introduction to statistical learning, covering regression model evaluation and various metrics, including MAE.
sklearn.metrics.mean_absolute_error, scikit-learn Development Team, 2024 - Official documentation for the Mean Absolute Error (MAE) function within the scikit-learn library, offering a technical specification and usage examples.