Mixed problems for second order partial differential equations of parabolic and hyperbolic type
§ 46. Ellipticity and parabolicity § 47. Mixed problems § 48. Estimates of the solution of the first mixed problem § 49. Estimates of the difference between two solutions of the first mixed problem § 50. Uniqueness criteria for the solution of the first mixed problem § 51. Continuous dependence of the solution of the first mixed problem on initial and boundary values and on the right-hand sides of system § 52. Stability of the solution of the first mixed problem § 53. Preliminary remarks and lemmas referring to the second mixed problem § 54. Sufficient conditions for the existence of sign-stabilizing factors § 55. Analogues of theorems in § 48-52 in case of the second mixed problem § 56. Energy estimates for solutions of hyperbolic equations