... (4.7) The reasonings in the case of Wξ( f )(z) are similar. The proof of continuity on D of Wξ( f )and W∗ξ( f ) i s similar to that for Pξ( f )intheproofofTheorem 2.1(i).It remains to ... kuu2+ ξ22du. (3.7) The continuity of f onD implies the continuity of Qξ( f ), Q∗ξ( f ), and Rξ( f )asintheproof of Theorem 2.1(i) for Pξ( f ).It remains to show that b1(ξ) ... ; ξ)∂D(2.8) (for the last inequalities, see, e.g., [2, proof of Theorem 2.1(i), page 252]).Remark 2.2. Theorem 2.1(ii) and (iii) remain valid for f only continuous on D. In what follows,...