@article{SPHM_1981___3_A1_0,
     author = {Perelman, Ch.},
     title = {Logique formelle et logique informelle},
     journal = {S\'eminaire de Philosophie et Math\'ematiques},
     pages = {1--7},
     publisher = {IREM Paris-Nord~; \'Ecole Normale Sup\'erieure},
     number = {3},
     year = {1981},
     language = {fr},
     url = {http://www.numdam.org/item/SPHM_1981___3_A1_0/}
}