1. The parametrix and the propagation of the wave front of solutions of the Cauchy problem for a model equation;Alexandrian;Izv. Akad. Nauk Armyan. SSR Ser. Mat.,1984
2. An example of a weakly hyperbolic Cauchy problem not well posed in C∞;Colombini;Acta Math.,1982
3. Local existence for semilinear weakly hyperbolic equations with time dependent coefficients;D'Ancona;Nonlinear Anal.,1993
4. On the Cauchy problem for 2×2 weakly hyperbolic systems;Ebert;Osaka J. Math.,2005
5. Necessary conditions for the well posedness of the Cauchy problem for nonstrictly equations;Ivrii;Uspekhi Mat. Nauk,1974