Formulas for the variation of the solution of a differential equation with retarded arguments and with a continuous initial condition (Q2387920)

Another paper with similar title and content. Compare, e.g., the second author and \textit{L. Alkhazishvili} [Mem. Differ. Equ. Math. Phys. 31, 83--97 (2004; Zbl 1077.34079)] and the authors [Sb. Math. 196, No. 8, 1137--1163 (2005); translation from Mat. Sb. 196, No. 8, 49--74 (2005; Zbl 1094.34536)].