@article{01310485, title = {Oscillation and nonoscillation criteria for two-dimensional systems of first-order linear ordinary differential equations.}, journal = {Georgian Mathematical Journal}, volume = {6}, year = {1999}, pages = {285-298}, doi = {10.1023/A:1022187214750}, zbl = {0930.34025}, language = {en}, url = {http://dml.mathdoc.fr/item/01310485} }
Lomtatidze, A.; Partsvania, N. Oscillation and nonoscillation criteria for two-dimensional systems of first-order linear ordinary differential equations.. Georgian Mathematical Journal, Tome 6 (1999) pp. 285-298. doi : 10.1023/A:1022187214750. http://gdmltest.u-ga.fr/item/01310485/