@article{1077465337, author = {Herbst, Robert Taylor}, title = {Reduction of differential systems to first order}, journal = {Duke Math. J.}, volume = {20}, number = {1}, year = {1953}, pages = { 481-487}, language = {en}, url = {http://dml.mathdoc.fr/item/1077465337} }
Herbst, Robert Taylor. Reduction of differential systems to first order. Duke Math. J., Tome 20 (1953) no. 1, pp. 481-487. http://gdmltest.u-ga.fr/item/1077465337/