@article{CMUC_1981__22_4_a6,
     author = {Nakhmanson, L. V. and Yakovlev, N. N.},
     title = {O {\cyrb}{\cyri}{\cyrk}o{\cyrm}{\cyrp}a{\cyrk}{\cyrt}ax, {\cyrl}e{\cyrzh}a{\cyrshch}{\cyri}x {\cyrv}  $\sigma$-{\cyrp}po{\cyri}{\cyrz}{\cyrv}e{\cyrd}e{\cyrn}{\cyri}{\cyrya}x},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {705--719},
     publisher = {mathdoc},
     volume = {22},
     number = {4},
     year = {1981},
     mrnumber = {647019},
     zbl = {0499.54006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1981__22_4_a6/}
}