The Python Tutorial - 3. An Informal Introduction to Python, Guido van Rossum and the Python Development Team, 2023 (Python Software Foundation) - Provides an official and concise introduction to Python's fundamental concepts, including variable assignment and basic data types.
Introduction to Computer Science and Programming in Python, Fall 2016, John Guttag, Ana Bell, Eric Grimson, 2016 (MIT OpenCourseWare) - A foundational university course that covers basic Python concepts like variables, data types, and expressions through video lectures and problem sets.