pandas.crosstab, pandas development team, 2024 - Official documentation for the pandas.crosstab function, detailing its usage, parameters, and examples for creating contingency tables.
OpenIntro Statistics, David Diez, Mine Çetinkaya-Rundel, and Christopher Barr, 2023 (OpenIntro) - Provides a conceptual foundation for understanding contingency tables, marginal distributions, and conditional distributions in statistical analysis.