@article{DE_1979_15_4_a1,
     author = {\`E. I. Grudo},
     title = {Analogues of the fundamental theorems of the first method of {Ljapunov} for {Pfaffian} systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {589--599},
     publisher = {mathdoc},
     volume = {15},
     number = {4},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1979_15_4_a1/}
}