@article{MZM_1986_39_6_a8,
     author = {D. B. Shakhmatov},
     title = {Precalibers of $\sigma$-compact topological groups},
     journal = {Matemati\v{c}eskie zametki},
     pages = {859--868},
     year = {1986},
     volume = {39},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1986_39_6_a8/}
}