- https://math.stackexchange.com/questions/23312/what-is-the-importance-of-eigenvalues-eigenvectors/3503875#3503875
- https://math.stackexchange.com/questions/1520832/real-life-examples-for-eigenvalues-eigenvectors
- https://matheducators.stackexchange.com/questions/520/what-is-a-good-motivation-showcase-for-a-student-for-the-study-of-eigenvalues