@article{DAN_1974_214_6_a4,
     author = {M. V. Karasev},
     title = {Expansion of functions of noncommuting operators},
     journal = {Doklady Akademii Nauk},
     pages = {1254--1257},
     year = {1974},
     volume = {214},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1974_214_6_a4/}
}