@article{MAN_1975__216_162722,
     author = {Gordon Wassermann},
     title = {Stability of {Caustics.}},
     journal = {Mathematische Annalen},
     pages = {43--50},
     publisher = {mathdoc},
     volume = {216},
     year = {1975},
     zbl = {0293.58008},
     url = {http://geodesic.mathdoc.fr/item/MAN_1975__216_162722/}
}