@article{MZ_1987__196_173875,
     author = {Jih-Hsin Cheng},
     title = {On the {Curvature} of {CR-Structures} and its {Covariant} {Derivatives.}},
     journal = {Mathematische Zeitschrift},
     pages = {203--210},
     publisher = {mathdoc},
     volume = {196},
     year = {1987},
     url = {http://geodesic.mathdoc.fr/item/MZ_1987__196_173875/}
}