@article{DAN_1976_227_2_a15,
     author = {K. S. Matviychuk},
     title = {The mathematical description of quantum systems by the method of reduced density matrices of the canonical ensemble},
     journal = {Doklady Akademii Nauk},
     pages = {318--320},
     publisher = {mathdoc},
     volume = {227},
     number = {2},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_227_2_a15/}
}