@article{ZNSL_1987_157_a8,
     author = {N. A. Shirokov},
     title = {She quantitative version of the {Kado} theorem},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {103--112},
     publisher = {mathdoc},
     volume = {157},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1987_157_a8/}
}