  In this paper, we show an approximation in law, in the space of the
continuous functions on $[0,1]^2$, of two-parameter Gaussian processes that can
be represented as a Wiener type integral by processes constructed from
processes that converge to the Brownian sheet. As an application, we obtain a
sequence of processes constructed from a L\'evy sheet that converges in law
towards the fractional Brownian sheet.
