@article{DE_1989_25_11_a5,
     author = {\`E. I. Grudo},
     title = {On the structure of the solutions of a periodic {Pfaffian} system with two purely imaginary roots in the characteristic equation},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1867--1872},
     publisher = {mathdoc},
     volume = {25},
     number = {11},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_11_a5/}
}