@article{MM2_1989__63_3_155368,
     author = {Thomas Peternell},
     title = {Singular sufaces and the rigidity of {IP3.}},
     journal = {Manuscripta mathematica},
     pages = {69--82},
     publisher = {mathdoc},
     volume = {63},
     number = {3},
     year = {1989},
     zbl = {0679.32022},
     url = {http://geodesic.mathdoc.fr/item/MM2_1989__63_3_155368/}
}