This book consists of five chapters. The first chapter is devoted to the historical background and introductory concepts. Partial complex differentiations in the classical sense and in the sense of Sobolev, generalized analytic functions, associated differential operators, associated spaces and interior estimates are introduced in Chapter II. The interior estimate for holomorphic functions in the supremum-norm is also obtained. In Chapter III, first, the concept of scales of Banach spaces are presented. In Chapter IV, initial value problems defined by Son and Tutschke 25].In the last...