  The experimental response functions of 7^Li nucleus at effective 3-momentum
transfers q = 1.250; 1.375; 1.500 and 1.625 fm^{-1} are presented. The
longitudinal response functions were used to evaluate the Coulomb sum values.
The Coulomb sums for 6^Li obtained by us earlier were applied to analyze these
data. The Coulomb sums of lithium isotopes were compared with the well-known
Coulomb sums values of the other nuclei.
