@article{SEDP_1981-1982____A18_0,
     author = {Geymonat, G.},
     title = {Perturbations en th\'eorie spectrale},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:19},
     pages = {1--13},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1981-1982},
     mrnumber = {671616},
     zbl = {0493.35066},
     language = {fr},
     url = {http://www.numdam.org/item/SEDP_1981-1982____A18_0/}
}