@article{AULFM_1991_04_a6,
     author = {Pawlak, Ryszard J.},
     title = {On {Darboux} points and the perfectly closed class of functions},
     journal = {Acta Universitatis Lodziensis. Folia Mathematica},
     publisher = {mathdoc},
     volume = {04},
     year = {1991},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AULFM_1991_04_a6/}
}