@article{GAU_1973-1974__1__A2_0,
     author = {Robba, Philippe},
     title = {Indice d'un op\'erateur diff\'erentiel},
     journal = {Groupe de travail d'analyse ultram\'etrique},
     note = {talk:2},
     pages = {1--14},
     publisher = {Secr\'etariat math\'ematique},
     volume = {1},
     year = {1973-1974},
     mrnumber = {447248},
     zbl = {0375.34003},
     language = {fr},
     url = {http://www.numdam.org/item/GAU_1973-1974__1__A2_0/}
}