@article{1102971648, author = {Villone, Arnold L.}, title = {Self-adjoint differential operators.}, journal = {Pacific J. Math.}, volume = {35}, number = {3}, year = {1970}, pages = { 517-531}, language = {en}, url = {http://dml.mathdoc.fr/item/1102971648} }
Villone, Arnold L. Self-adjoint differential operators.. Pacific J. Math., Tome 35 (1970) no. 3, pp. 517-531. http://gdmltest.u-ga.fr/item/1102971648/