L13A
        1. Christoffel Symbols

L13B
        1. Christoffel Symbols (cont.)
        2. Christoffel Symbols in Terms of the First Fundamental
            Form

L13C
        1. All Geometric Concepts and Properties Expressed in
            Terms of the Christoffel Symbols Are Invariant under Isometry
        2. Codazzi-Mainardi Equations