@article{ZVMMF_1968_8_4_a8,
     author = {N. V. Petri and Kh. D. Ikramov},
     title = {Extremal properties of some matrix norms},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {865--871},
     year = {1968},
     volume = {8},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1968_8_4_a8/}
}