“…Consequently, in order to obtain an existence and uniqueness of a solution to problem with x 0 =0, it suffices to show that there exists a unique solution to problem such that So, we have the following. Theorem If , then problem possesses a unique solution in . Proof In order to prove this result, one can use analogous arguments as in , proof of theorem 4]. So, we give only a brief overview of the proof.…”