@article{GDZPPN002285606, title = {\"Uber infinitesimale Kerne von Punktmengen in topologischen R\"aumen.}, journal = {Mathematische Annalen}, volume = {133}, year = {1957}, pages = {52-78}, zbl = {0077.16502}, url = {http://dml.mathdoc.fr/item/GDZPPN002285606} }
Wagner, K. Über infinitesimale Kerne von Punktmengen in topologischen Räumen.. Mathematische Annalen, Tome 133 (1957) pp. 52-78. http://gdmltest.u-ga.fr/item/GDZPPN002285606/