  In this paper, expectation values of exponential fields in the 2-dimensional
Euclidean sine-Gordon field theory are calculated with variational perturbation
approach up to the second order. Our numerical analysis indicates that for not
large values of the exponential-field parameter $a$, our results agree very
well with the exact formula conjectured by Lukyanov and Zamolodchikov in Nucl.
Phys. B 493, 571 (1997).
