Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1979_15_9_a2, author = {\`E. I. Grudo and L. F. Yanchuk}, title = {On the general theory of {Pfaffian} systems}, journal = {Differencialʹnye uravneni\^a}, pages = {1562--1571}, publisher = {mathdoc}, volume = {15}, number = {9}, year = {1979}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1979_15_9_a2/} }
È. I. Grudo; L. F. Yanchuk. On the general theory of Pfaffian systems. Differencialʹnye uravneniâ, Tome 15 (1979) no. 9, pp. 1562-1571. http://geodesic.mathdoc.fr/item/DE_1979_15_9_a2/