1. V. I. Arnold, A. N. Varchenko, and S. M. Gusein-Zade, Singularities of Differentiable Mappings, Vol. I, Birkhauser (1984).
2. V. I. Arnold, “Indices of singular points of 1-forms on a manifold with boundary, the convolution of invariants of groups generated by reflections, and the singular projections of smooth surfaces,” Usp. Mat. Nauk,34, No. 2, 3–38 (1979).
3. A. B. Givental, “Singular Lagrangian manifolds and their Lagrangian mappings,” Itogi Nauki i Tekhniki. Sovremennye Problemy Matematiki. Noveishie Dostizheniya [in Russian], Vol. 33, VINITI (1988), pp. 55–112.
4. V. V. Goryunov, “Singularities of projections of complete intersections,” Itogi Nauki i Tekhniki, Sovremennye Problemy Matematiki [in Russian], Vol. 22, VINITI (1983), pp. 167–206.
5. V. V. Lychagin, “Geometrical theory of singularities of solutions to nonlinear differential equations,” Problemy Geometrii [in Russian], Vol. 20, VINITI (1988), pp. 207–247.