1. [1] S. Bell and E. Ligocko, A simplification and extension of Fefferman's theorem on biholomorphic mappings, to appear.
2. [2] J. D'Angelo, Real hypersurfaces with degenerate Levi form, thesis, Princeton University, 1976.
3. [3] K. Diederich and J. Fornaess, Pseudoconvex domains with real-analytic boundary, Ann. Math. (2) 107 (1978), no. 2, 371–384.
4. [4] R. Gunning and H. Rossi, Analytic functions of several complex variables, Prentice-Hall Inc., Englewood Cliffs, N.J., 1965.
5. [5] J. J. Kohn, Subellipticity of the $\bar \partial$-Neumann problem on pseudo-convex domains: sufficient conditions, Acta Math. 142 (1979), no. 1-2, 79–122.