On the mean values of an entire function represented by dirichlet series of several complex variables

Let $f(s_1,s_2)$ be an entire function represented by Dirichlet series of two complex variables. We have defined for $0<\delta<\infty$ and $k_1,k_2>0$ the functions $I_\delta(\sigma_1,\sigma_2), A_\delta (\sigma_1,\sigma_2)$ and $G_{\delta,k_1,k_2}(\sigma_1,\sigma_2)$, then the Ritt-order $\rho$, the lower order $\lambda$ and the orders $\rho_1,\rho_2$ with respect to the variables $s_1,s_2$ could be expressed in terms of theses functions.