@article{DAN_1978_239_3_a11,
     author = {M. G. Tkachenko},
     title = {Chains and cardinals},
     journal = {Doklady Akademii Nauk},
     pages = {546--549},
     year = {1978},
     volume = {239},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_239_3_a11/}
}