@article{TMF_1977_33_1_a5,
     author = {N. N. Bogolyubov (Jr.)},
     title = {Generalized theorems in the theory of model systems},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {67--85},
     publisher = {mathdoc},
     volume = {33},
     number = {1},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1977_33_1_a5/}
}