Raouf Doss, Two Generalizations of Titchmarsh's Convolution Theorem, Proceedings of the American Mathematical Society, Vol. 108, No. 4 (Apr., 1990), pp. 893-897 ...

This is an abstract version of the Cauchy-Kovalevska theorem which can be applied to equations other than partial-differential, e.g. to certain differential-convolution or, more generally, ...