@article{IVM_1978_3_a1,
     author = {D. L. Berman},
     title = {An averaging operator},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {10--14},
     publisher = {mathdoc},
     number = {3},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1978_3_a1/}
}