@article{DAN_1967_172_5_a4,
     author = {N. M. Ermolaeva},
     title = {Arithmetic sums of recursively-projective sets},
     journal = {Doklady Akademii Nauk},
     pages = {1011--1013},
     publisher = {mathdoc},
     volume = {172},
     number = {5},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_172_5_a4/}
}