@article{1102969568, author = {Johnson, H. H.}, title = {Conditions for isomorphism in partial differential equations.}, journal = {Pacific J. Math.}, volume = {39}, number = {3}, year = {1971}, pages = { 401-406}, language = {en}, url = {http://dml.mathdoc.fr/item/1102969568} }
Johnson, H. H. Conditions for isomorphism in partial differential equations.. Pacific J. Math., Tome 39 (1971) no. 3, pp. 401-406. http://gdmltest.u-ga.fr/item/1102969568/