@article{10_4064_cm_2_1_40_45,
     author = {Norman Levinson},
     title = {On stability of non-linear systems of differential equations},
     journal = {Colloquium Mathematicum},
     pages = {40--45},
     publisher = {mathdoc},
     volume = {2},
     number = {1},
     year = {1949},
     doi = {10.4064/cm-2-1-40-45},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-2-1-40-45/}
}