@article{MAN_1971__194_162192,
     author = {Vasile ISTRATESCU and Ioana ISTRATESCU},
     title = {On {Some} {Classes} of {Operators} {II.}},
     journal = {Mathematische Annalen},
     pages = {126--134},
     publisher = {mathdoc},
     volume = {194},
     year = {1971},
     zbl = {0211.44202},
     url = {http://geodesic.mathdoc.fr/item/MAN_1971__194_162192/}
}