@book{MSMF_1977__51-52_,
     author = {Collectif},
     title = {Contributions \`a l'\'etude des op\'erateurs elliptiques et hypoelliptiques},
     series = {M\'emoires de la Soci\'et\'e Math\'ematique de France},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {51-52},
     year = {1977},
     language = {mul},
     url = {http://www.numdam.org/item/MSMF_1977__51-52_/}
}