@article{MP_1961_a23,
     author = {V. I. Levin},
     title = {{\CYRO} {\cyrch}{\cyri}{\cyrs}{\cyrl}{\cyre}~$\epsilon$},
     journal = {Matematicheskoe Prosveshchenie},
     pages = {256--257},
     publisher = {mathdoc},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MP_1961_a23/}
}