@article{PMF_1919_30_1_a9,
     author = {Mazurkiewicz, Stefan},
     title = {O zwi\k{a}zku mi\k{e}dzy istnieniem drugiej pochodnej uog\'olnionej a ci\k{a}g{\l}o\'sci\k{a} funkcyi},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {225--242},
     publisher = {mathdoc},
     volume = {30},
     number = {1},
     year = {1919},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/item/PMF_1919_30_1_a9/}
}