@article{1256054992, author = {Johnson, H. H.}, title = {Absolute equivalence of exterior differential systems}, journal = {Illinois J. Math.}, volume = {10}, number = {4}, year = {1966}, pages = { 407-411}, language = {en}, url = {http://dml.mathdoc.fr/item/1256054992} }
Johnson, H. H. Absolute equivalence of exterior differential systems. Illinois J. Math., Tome 10 (1966) no. 4, pp. 407-411. http://gdmltest.u-ga.fr/item/1256054992/