Working with missing data, The Pandas Development Team, 2023 - Official documentation explaining how Pandas represents and detects missing values using NaN, None, isnull(), isna(), and related methods.
Python for Data Analysis, Wes McKinney, 2022 (O'Reilly Media) - Foundational book by the creator of Pandas, covering data handling, cleaning, and preprocessing techniques, including identifying missing data.
Python Bar Charts, Plotly Technologies Inc., 2023 (Plotly Technologies Inc.) - Official documentation for creating bar charts with Plotly in Python, providing examples relevant to visualizing missing data counts.