@article{1183497369, author = {Thomas, J. M.}, title = {The condition for a pfaffian system in involution}, journal = {Bull. Amer. Math. Soc.}, volume = {40}, number = {12}, year = {1934}, pages = { 316-320}, language = {en}, url = {http://dml.mathdoc.fr/item/1183497369} }
Thomas, J. M. The condition for a pfaffian system in involution. Bull. Amer. Math. Soc., Tome 40 (1934) no. 12, pp. 316-320. http://gdmltest.u-ga.fr/item/1183497369/