@article{GMJ_2004__11_1_51354,
     author = {Pol\'ak, L.},
     title = {Oscillation and nonoscillation criteria for two-dimensional systems of linear ordinary differential equations.},
     journal = {Georgian Mathematical Journal},
     pages = {137--154},
     publisher = {mathdoc},
     volume = {11},
     number = {1},
     year = {2004},
     zbl = {1064.34019},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/GMJ_2004__11_1_51354/}
}