The Relation Between the Differentiability of Solution and Lower-order Terms of the Cauchy Problem for a Class of Weakly Hyperbolic Equations with Singular Coefficients. J. Part. Diff. Eq. [Internet]. 1991 Apr. 1 [cited 2026 Mar. 15];4(1):45-56. Available from: https://gsp.tricubic.dev/jpde/article/view/3672