@article{DAN_1969_186_1_a6,
     author = {N. V. Petri},
     title = {Complexity of algorithms and their operation time},
     journal = {Doklady Akademii Nauk},
     pages = {30--31},
     publisher = {mathdoc},
     volume = {186},
     number = {1},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_186_1_a6/}
}