@article{IZKAB_2015_6-2_a28,
     author = {A. A. Temirov},
     title = {Concept of two-level
},
     journal = {News of the Kabardin-Balkar scientific center of RAS},
     pages = {183--191},
     publisher = {mathdoc},
     number = {6-2},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IZKAB_2015_6-2_a28/}
}