@article{BSMF_1982__110__357_0,
     author = {Cenzer, Douglas and Mauldin, R. Daniel},
     title = {On the {Borel} class of the derived set operator},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {357--380},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {110},
     year = {1982},
     doi = {10.24033/bsmf.1968},
     mrnumber = {85b:54058},
     zbl = {0514.54027},
     language = {en},
     url = {http://archive.numdam.org/articles/10.24033/bsmf.1968/}
}