@article{SEDP_1972-1973____A28_0,
     author = {Grubb, G.},
     title = {Syst\`emes elliptiques ayant un spectre essentiel},
     journal = {S\'eminaire \'Equations aux d\'eriv\'ees partielles (Polytechnique) dit aussi "S\'eminaire Goulaouic-Schwartz"},
     note = {talk:27},
     pages = {1--11},
     publisher = {Ecole Polytechnique, Centre de Math\'ematiques},
     year = {1972-1973},
     mrnumber = {410074},
     zbl = {0274.35034},
     language = {fr},
     url = {http://www.numdam.org/item/SEDP_1972-1973____A28_0/}
}