References
- A. Lax, On Cauchy's problem for partial differential equations with multiple characteristics, Comm. Pure Appl. Math. 9(1956), 135-169. https://doi.org/10.1002/cpa.3160090203
- B. Midodashvili, A nonlocal problem for fourth order hyperbolic equations with multiple characteristics, Electron. J. Diff. Eqns. 85(2002), 1-7.
- F. Colombini and T. Kinoshita, On the weakly hyperbolic equation of 4th order, Hokkaido Math. J. 31(2002), 39-60.
- H. O. Kreiss, Initial boundary value problems for hyperbolic systems, Communs Pure and Appl. Math. 23(1970), 277-298. https://doi.org/10.1002/cpa.3160230304
- L. Bougoffa, The Cauchy problem for nonlinear Hyperbolic equations of higher order using Modified decomposition method, J. Math. Cont. Sc. and Appl, 1(2007), 11-19.
- M. D. Bronstein, The Cauchy problem for hyperbolic operators with characteristics of variable multiplicity, Trudy Moskov. Mat. Obsc. 41(1980), 87-103.
- M. S. Agranovich, Boundary value problems for systems with a parameter, Matem. Sbornik, 84(1971), No. 1, 27-65(Russian; Engl.transl. in Math. USSR Sbornik 13(1971), 27-65.
- R. Beals, Hyperbolic equations and systems with multiple characteristics, Arch. Rational Mech. Anal. 48(1972), 123-152..
- S. Agmon, Probleme mixte pour les equations hyperboliques d'ordre superieur, Colloq. Intern. CNRS, Paris (1962), 1-6.
- Y. Ohya and S. Tarama, Le probleme de Cauchy a caracteristiques multiples coefficients holderiens en t, Proc. Taniguchi International Symposium on Hyperbolic Equations and Related Topics (1984), 273-306.