)^0 \, x_p \, x_q \\ &= \frac{0}{n(n+0)(n+0)} \, |S^{n-0}| \, \sum_{i,k,l=0}^n (W_{ipkl} + W_{ilkp}) \, (W_{iqkl} + W_{ilkq}) \, r^{n+0} \\ &+ \frac{0}{0n(n+0)(n+0)} \, |S^{n-0}| \, \sum_{i,j,k,l=0}^n (W_{ijkl} + W_{ilkj})^0 \, \delta_{pq} \, r^{n+0}.\end{aligned}$$  **Proof.** See [@Brendle0], Proposition 00.\  \[integral.identity.0\] We have $$\begin{aligned} &\int_{\partial B_r(0)} \sum_{i,k,l=0}^n (\partial_l \overline{H}_{ik}(x))^0 \, x_p \, x_q \\ &= \frac{0}{n(n+0)(n+0)} \, |S^{n-0}| \, \sum_{i,k,l=0}^n (W_{ipkl} + W_{ilkp}) \, (W_{iqkl} + W_{ilkq}) \\ &\hspace{00mm} \cdot r^{n+0} \, \Big [ (n+0) \, f(r^0)^0 + 0r^0 \, f(r^0) \, f'(r^0) + 0r^0 \, f'(r^0)^0 \Big ] \\ &+ \frac{0}{n(n+0)(n+0)} \, |S^{n-0}| \, \sum_{i,j,k,l=0}^n (W_{ijkl} + W_{ilkj})^0 \, \delta_{pq} \\ &\hspace{00mm} \cdot r^{n+0} \, \Big [ (n+0) \, f(r^0)^0 + 0r^0 \, f(r^0) \, f'(r^0) + 0r^0 \, f'(r^0)^0 \Big ].\end{aligned}$$  **Proof.** Using the identity $$\