@article{CMUC_1973__14_4_a2, author = {Doktor, Pavel}, title = {On the density of smooth functions in certain subspaces of {Sobolev} space}, journal = {Commentationes Mathematicae Universitatis Carolinae}, pages = {609--622}, publisher = {mathdoc}, volume = {14}, number = {4}, year = {1973}, mrnumber = {0336317}, zbl = {0268.46036}, language = {en}, url = {http://geodesic.mathdoc.fr/item/CMUC_1973__14_4_a2/} }