1. Singularities of Differentiable Maps. Vol. I. The Classification of Critical Points, Caustics and Wave Fronts;Arnol'd,1985
2. Cusps of Gauss Mappings;Banchoff,1982
3. Families of surfaces: height functions, Gauss maps and duals;Bruce,1995
4. Geometric Theory of Foliations;Camacho,1985
5. Stable Mappings and Their Singularities;Golubitsky,1976