@article{TMF_1975_24_1_a7,
     author = {N. E. Tyurin},
     title = {Lower bounds for the $U$ matrix},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {62--70},
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1975_24_1_a7/}
}