Div, Grad, Curl, and All That: An Informal Text on Vector Calculus by H.M. Schey (Rochester Institute of Technology)
Since the publication of the First Edition over thirty years ago, Div, Grad, Curl, and All That has been widely renowned for its clear and concise coverage of vector calculus, helping science and engineering students gain a thorough understanding of gradient, curl, and Laplacian operators without required knowledge of advanced mathematics.