@article{GDZPPN002215322, title = {Graphens\"atze f\"ur topologische R\"aume.}, journal = {Manuscripta mathematica}, volume = {1}, year = {1969}, pages = {111-124}, zbl = {0167.51204}, url = {http://dml.mathdoc.fr/item/GDZPPN002215322} }
Niessen, Heinz-Dieter. Graphensätze für topologische Räume.. Manuscripta mathematica, Tome 1 (1969) pp. 111-124. http://gdmltest.u-ga.fr/item/GDZPPN002215322/