@article{DAN_1989_304_6_a1,
     author = {V. I. Zubov},
     title = {Integral invariants of asymptotically stable systems of},
     journal = {Doklady Akademii Nauk},
     pages = {1293--1294},
     publisher = {mathdoc},
     volume = {304},
     number = {6},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_304_6_a1/}
}