Introduction to Linear Algebra, Gilbert Strang, 2016 (Wellesley-Cambridge Press) - A standard textbook for linear algebra, providing a rigorous yet accessible introduction to matrix definitions, dimensions, and element indexing.
Linear Algebra Review and Background, Andrew Ng, 2022Stanford University CS229 Lecture Notes - A concise review of essential linear algebra concepts, including matrix definitions and indexing, serving as a prerequisite for machine learning.
NumPy indexing, NumPy Developers, 2023 (NumPy Project) - Official documentation detailing 0-based indexing for NumPy arrays, which represent matrices in Python, and contrasts with mathematical 1-based indexing.