@article{oai:repository.dl.itc.u-tokyo.ac.jp:00039416, author = {Kakie, Kunio}, issue = {3}, journal = {Journal of the Faculty of Science, the University of Tokyo. Sect. 1 A, Mathematics = 東京大学理学部紀要. 第1類A, 数学}, month = {}, note = {application/pdf}, pages = {537--569}, title = {On the integration of involutive systems of non-linear partial differential equations}, volume = {36}, year = {1989} }