@article{DAN_1975_224_4_a9,
     author = {V. V. Petrov and A. V. Zaporozhets},
     title = {A principle for evolving systems},
     journal = {Doklady Akademii Nauk},
     pages = {779--782},
     publisher = {mathdoc},
     volume = {224},
     number = {4},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_224_4_a9/}
}