@incollection{JEDP_1974____A4_0,
     author = {Baouendi, Mohamed Salah and Sj\"ostrand, Johannes},
     title = {R\'egularit\'e analytique pour des op\'erateurs elliptiques singuliers en un point},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {4},
     pages = {1--7},
     publisher = {Ecole polytechnique},
     year = {1974},
     language = {fr},
     url = {http://archive.numdam.org/item/JEDP_1974____A4_0/}
}