@incollection{SB_1976-1977__19__19_0,
     author = {Duistermaat, J. J.},
     title = {The light in the neighborhood of a caustic},
     booktitle = {S\'eminaire Bourbaki : vol. 1976/77, expos\'es 489-506},
     series = {S\'eminaire Bourbaki},
     note = {talk:490},
     pages = {19--29},
     publisher = {Springer-Verlag},
     number = {19},
     year = {1978},
     mrnumber = {521757},
     zbl = {0401.35063},
     language = {en},
     url = {http://www.numdam.org/item/SB_1976-1977__19__19_0/}
}