In a world where academic textbooks try to impress you with their difficulty, Kay tries to teach you. That makes him a hero.
Mastering Tensor Calculus: A Guide to the Schaum's Outline by David Kay
) that defines distances, angles, and the volume element in a given space. It is used to raise or lower indices on other tensors.
: Covers the summation convention (Einstein notation), which is essential for making tensor results surveyable.