@article{700869,
     title = {Syntopogene halbgruppen},
     booktitle = {General Topology and its Relations to Modern Analysis and Algebra},
     series = {GDML\_Books},
     publisher = {Academia Publishing House of the Czechoslovak Academy of Sciences},
     address = {Praha},
     year = {1967},
     pages = {101-102},
     mrnumber = {MR0231936},
     zbl = {0199.34002},
     url = {http://dml.mathdoc.fr/item/700869}
}

Császár, Á. Syntopogene halbgruppen, dans General Topology and its Relations to Modern Analysis and Algebra, GDML_Books,  (1967), pp. 101-102. http://gdmltest.u-ga.fr/item/700869/