@article{DAN_1962_144_5_a5,
     author = {R. A. DeMarr},
     title = {Transformations in semi-groups and multi-valued mappings},
     journal = {Doklady Akademii Nauk},
     pages = {968--970},
     publisher = {mathdoc},
     volume = {144},
     number = {5},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_144_5_a5/}
}