@article{DAN_1958_119_6_a11,
     author = {K. A. Mikhailova},
     title = {The entrance problem for direct unions of groups},
     journal = {Doklady Akademii Nauk},
     pages = {1103--1105},
     publisher = {mathdoc},
     volume = {119},
     number = {6},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_119_6_a11/}
}