Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{MZ_1967__98_170757, author = {Johann Walter}, title = {Symmetrie elliptischer {Differentialoperatoren.}}, journal = {Mathematische Zeitschrift}, pages = {401--406}, publisher = {mathdoc}, volume = {98}, year = {1967}, zbl = {0146.34302}, url = {http://geodesic.mathdoc.fr/item/MZ_1967__98_170757/} }
Johann Walter. Symmetrie elliptischer Differentialoperatoren.. Mathematische Zeitschrift, Tome 98 (1967), pp. 401-406. http://geodesic.mathdoc.fr/item/MZ_1967__98_170757/