@incollection{AST_1973__2-3__197_0, author = {Helffer, Bernard and Kannai, Yakar}, title = {Determining factors and hypoellipticity of ordinary differential operators with double "characteristics"}, booktitle = {Colloque International C.N.R.S. sur les \'equations aux d\'eriv\'ees partielles lin\'eaires}, series = {Ast\'erisque}, pages = {197--216}, publisher = {Soci\'et\'e math\'ematique de France}, number = {2-3}, year = {1973}, mrnumber = {402260}, zbl = {0272.34006}, language = {en}, url = {http://archive.numdam.org/item/AST_1973__2-3__197_0/} }
TY - CHAP AU - Helffer, Bernard AU - Kannai, Yakar TI - Determining factors and hypoellipticity of ordinary differential operators with double "characteristics" BT - Colloque International C.N.R.S. sur les équations aux dérivées partielles linéaires AU - Collectif T3 - Astérisque PY - 1973 SP - 197 EP - 216 IS - 2-3 PB - Société mathématique de France UR - http://archive.numdam.org/item/AST_1973__2-3__197_0/ LA - en ID - AST_1973__2-3__197_0 ER -
%0 Book Section %A Helffer, Bernard %A Kannai, Yakar %T Determining factors and hypoellipticity of ordinary differential operators with double "characteristics" %B Colloque International C.N.R.S. sur les équations aux dérivées partielles linéaires %A Collectif %S Astérisque %D 1973 %P 197-216 %N 2-3 %I Société mathématique de France %U http://archive.numdam.org/item/AST_1973__2-3__197_0/ %G en %F AST_1973__2-3__197_0
Helffer, Bernard; Kannai, Yakar. Determining factors and hypoellipticity of ordinary differential operators with double "characteristics", in Colloque International C.N.R.S. sur les équations aux dérivées partielles linéaires, Astérisque, no. 2-3 (1973), pp. 197-216. http://archive.numdam.org/item/AST_1973__2-3__197_0/
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