@article{FAA_1987_21_4_a0,
     author = {A. N. Varchenko and I. M. Gel'fand},
     title = {Heaviside functions of a configuration of hyperplanes},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {1--18},
     publisher = {mathdoc},
     volume = {21},
     number = {4},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1987_21_4_a0/}
}