@article{DAN_1965_163_2_a10,
     author = {M. N. Yakovlev},
     title = {Estimates of the $H$-condition numbers of matrices in the {Petrov{\textendash}Galerkin} method},
     journal = {Doklady Akademii Nauk},
     pages = {309--310},
     year = {1965},
     volume = {163},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1965_163_2_a10/}
}