@incollection{JEDP_1976____A4_0, author = {Bolley, Pierre and Camus, Jacques}, title = {R\'egularit\'e pour des syst\`emes \`a coefficients constants}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {4}, pages = {1--19}, publisher = {Ecole polytechnique}, year = {1976}, language = {fr}, url = {http://www.numdam.org/item/JEDP_1976____A4_0/} }