@article{ASNSP_1986_4_13_2_299_0, author = {Mc Kean, H. P. and Scovel, J. C.}, title = {Geometry of some simple nonlinear differential operators}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, pages = {299--346}, publisher = {Scuola normale superiore}, volume = {Ser. 4, 13}, number = {2}, year = {1986}, mrnumber = {876127}, zbl = {0648.47048}, language = {en}, url = {http://www.numdam.org./item/ASNSP_1986_4_13_2_299_0/} }