@article{700862,
     title = {Structure of Tchebychev sets},
     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 = {356-358},
     zbl = {0165.14302},
     url = {http://dml.mathdoc.fr/item/700862}
}

Wulbert, D. E. Structure of Tchebychev sets, dans General Topology and its Relations to Modern Analysis and Algebra, GDML_Books,  (1967), pp. 356-358. http://gdmltest.u-ga.fr/item/700862/