@article{1256054459, author = {Beals, Richard}, title = {On eigenfunction expansions for elliptic operators}, journal = {Illinois J. Math.}, volume = {11}, number = {4}, year = {1967}, pages = { 663-668}, language = {en}, url = {http://dml.mathdoc.fr/item/1256054459} }
Beals, Richard. On eigenfunction expansions for elliptic operators. Illinois J. Math., Tome 11 (1967) no. 4, pp. 663-668. http://gdmltest.u-ga.fr/item/1256054459/