@article{SEDP_1970-1971____A2_0,
     author = {Derridj, M. and Zuily, C.},
     title = {R\'egularit\'e $C^\infty $ au bord d{\textquoteright}une classe d{\textquoteright}op\'erateurs d\'eg\'en\'er\'es},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:2},
     pages = {1--13},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1970-1971},
     zbl = {0243.35043},
     language = {fr},
     url = {http://www.numdam.org/item/SEDP_1970-1971____A2_0/}
}