  Let $S_\lambda F(x)$ be the spherical partial sums of the multiple Fourier
series of function $F\in L_2(\mathbb{T}^N)$. We prove almost-everywhere
convergence $S_\lambda F(x)\rightarrow F(x)$ for functions in Sobolev spaces
$H_p^a(\mathbb{T}^N)$ provided $1< p \leq 2$ and $a>
(N-1)(\frac{1}{p}-\frac{1}{2})$. For multiple Fourier integrals this is well
known result of Carbery and Soria (1988). To prove our result, we first extend
the transplantation technic of Kenig and Tomas (1980) from $L_p$ spaces to
$H_p^a$ spaces, then apply it to the Carbery and Soria result.
