@article{GDZPPN002105179, title = {A global invariant for three dimensional CR-manifolds.}, journal = {Inventiones mathematicae}, volume = {93}, year = {1988}, pages = {333-348}, zbl = {0643.32006}, url = {http://dml.mathdoc.fr/item/GDZPPN002105179} }
Burns, D.M. Jr.; Epstein, C.L. A global invariant for three dimensional CR-manifolds.. Inventiones mathematicae, Tome 93 (1988) pp. 333-348. http://gdmltest.u-ga.fr/item/GDZPPN002105179/