@article{ZNSL_1999_262_a1,
     author = {V. I. Vasyunin},
     title = {On a system of step functions},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {49--70},
     year = {1999},
     volume = {262},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1999_262_a1/}
}