L13_A
        1. Christoffel Symbols

L13_B
        1. Christoffel Symbols (cont.)
        2. Christoffel Symbols in Terms of the First Fundamental
            Form

L13_C
        1. All Geometric Concepts and Properties Expressed in
            Terms of the Christoffel Symbols Are Invariant under Isometry
        2. Codazzi-Mainardi Equations