Orthogonal Coordinate Systems - Cartesian, Cylindrical, and Spherical – Fosco Connect
How to differentiate unit vectors of spherical coordinates - Quora
Finding Information of a Curve using the Derivatives of r, x, & y with Respect to theta of r=f(theta), & the First and Second Derivatives of y with Respect to x
Polar derivatives
Solved 1. The relations between spherical and Cartesian | Chegg.com