|
[1] Ivey, T.A., Landsberg, J.M.: Cartan for beginners: differential geometry via moving frames and exterior differential systems. Graduate Studies in Mathematics, vol. 61. American Mathematical Society, Providence, RI (2003) [2] Lee, J.M.: The Fefferman metric and pseudohermitian invariants. Trans. Am. Math. Soc. 411–429 (1986) [3] Hung-Lin,Chiu:The Fundamental and rigidity theorems for pseudohermitian submanifolds(2018) [4] S. M. Webster, Pseudohermitian structures on a real hypersurface, J. Differential Geom. 13 (1978), 25-41. |