@article{DAN_1980_250_2_a1,
     author = {V. V. Ivanov},
     title = {Perturbation of uniformly summable semigroups of operators},
     journal = {Doklady Akademii Nauk},
     pages = {269--273},
     publisher = {mathdoc},
     volume = {250},
     number = {2},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1980_250_2_a1/}
}