content_image/325262.jpg content_image/325263.jpg content_image/325264.jpg content_image/325265.jpg content_image/325266.jpg content_image/325267.jpg content_image/325268.jpg
(A.17) by the Fubini-Tonelli theorem, we have 

<img src='content_image/325262.jpg'>

for each N > 0. By analogous reasoning, from (A.16), one can prove that 

<img src='content_image/325263.jpg'>

for ∣ $_{β}$′ ∣ ≤ 2, where M$_{1}$ > 0 is the maximum of the continuous functions 1 

and 

<img src='content_image/325264.jpg'>

<img src='content_image/325265.jpg'>

on D × G ′ . Inequalities (A.18) imply that ∂ β ′ ξ ′ ∂$_{η}$q, ∂ β ′ ξ ′ ∂$_{x}$ j ∂$_{η}$q ∈ L$_{2}$ ( Δ 1 η ) for ∣ $_{β}$′ ∣ ≤ 2. Moreover, taking into account Remark 2 after Lemma 2, from (A.11) we obtain 

In a similar manner, we can prove that 

<img src='content_image/325266.jpg'>

<img src='content_image/325267.jpg'>

Taking into account (4.5) and using arguments similar to the previous, it can be shown that 

<img src='content_image/325268.jpg'>

