@article{MT_1989_15_a1,
     author = {H. Ya. Bulgakov},
     title = {Justification of guaranteed accuracy for identifying invariant subspaces of nonselfadjoint matrices},
     journal = {Matemati\v{c}eskie trudy},
     pages = {12--93},
     year = {1989},
     volume = {15},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MT_1989_15_a1/}
}