PageHeader : Funkcialaj Ekvacioj, 31 (1988) 249-296 Title : A Systematization of the $\mathrm{L}^{2}$ -well-posed Mixed Problem and Title : its Applications to the Mixed Problem for Weakly Title : Hyperbolic Equations of Second Order AuthorInfo : By AuthorInfo : Masaru TANIGUCHI section : Introduction section : Proposition 1.2. We have section : Proposition 1.5. We have section : Proposition 1.7. We has section : §2. A systematization of an $\mathrm{L}^{2}$ -well-posed mixed problem section : §3. Mixed problem with zero initial data section : §4. The existence of the solution section : References