@article{700863,
     title = {Quelques d\'emonstrations nouvelles dans la th\'eorie des ensembles boreliens},
     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 = {131-132},
     zbl = {0162.54803},
     url = {http://dml.mathdoc.fr/item/700863}
}

Engelking, R. Quelques démonstrations nouvelles dans la théorie des ensembles boreliens, dans General Topology and its Relations to Modern Analysis and Algebra, GDML_Books,  (1967), pp. 131-132. http://gdmltest.u-ga.fr/item/700863/