L3A
       1.Review: Geometric Interpretation of Gauss Curvature
       2.Remark: Similar Result for Curvature of Plane Curve 
       3.Tangent Indicatrix
       4.Locally Convex and Strictly Locally Convex 

       
L3B
       1. Note: Relations between Curvature and Locally Convex

L3C
       1. Note: A Critical Point of a Distance Function on a Surface