@article{FORUM_1992__4_6_141686,
     author = {Niels Jacob},
     title = {Feller semigroups, {Dirchlet} forms, and pseudo differential operators.},
     journal = {Forum mathematicum},
     pages = {433--446},
     publisher = {mathdoc},
     volume = {4},
     number = {6},
     year = {1992},
     zbl = {0759.60078},
     url = {http://geodesic.mathdoc.fr/item/FORUM_1992__4_6_141686/}
}