@article{DAN_1974_217_4_a1,
     author = {V. V. V'yugin},
     title = {On upper semilattices of numerations},
     journal = {Doklady Akademii Nauk},
     pages = {749--751},
     publisher = {mathdoc},
     volume = {217},
     number = {4},
     year = {1974},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_217_4_a1/}
}