Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1971_7_6_a6, author = {L. V. Trigubovich}, title = {The periodic solutions of second and third order linear systems}, journal = {Differencialʹnye uravneni\^a}, pages = {1007--1011}, publisher = {mathdoc}, volume = {7}, number = {6}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1971_7_6_a6/} }
L. V. Trigubovich. The periodic solutions of second and third order linear systems. Differencialʹnye uravneniâ, Tome 7 (1971) no. 6, pp. 1007-1011. http://geodesic.mathdoc.fr/item/DE_1971_7_6_a6/