In the Wolfram Mathworld section on spherical coordinates there's given a list of nine covariant derivatives. The derivatives are given with respect to radius, azmuth, and zenith using the usual symbols r, theta and phi. The question is: what would be examples of the vectors whose derivatives are taken, sybolized by A(subscript)r, A(subscript)theta, and A(subscript)phi. These vectors appear explicitly on the right side of the equations. I would have expected the covariant derivatives to be of the position vector parameterized by r, theta, and phi, but not so. Anyone?