Hytonen, TuomasMcIntosh, AlanPortal, Pierre2015-12-071424-3199http://hdl.handle.net/1885/20674We study the boundedness of the H∞ functional calculus for differential operators acting in L p(Rn; CN).For constant coefficients, we give simple conditions on the symbols implying such boundedness. For non-constant coefficients, we extend our recent re201110.1007/s00028-010-0082-y2015-12-07