  Previously developed method for finding asymptotic solutions of Vlasov
equations using two-dimensional (in coordinate x and time t) Laplace transform
is applied to low-collision electron-ion plasmas. Taking into account Coulomb
collisions in the limit m_e << m_i, \bar{v_i} << \bar{v_e}, and T_e m_e << T_i
m_i, results in the expression for longitudinal high-frequency plasma-electron
oscillation/wave decrement essentially depending on oscillation frequency
\omega. This expression is quite different from the used one for low-frequency
plasma sound, which can be derived using expansion in asymptotically divergent
series in \delta/\omega_0, k v_i/\omega_0, where \delta is imaginary part of
the frequency \omega=\omega_0+i\delta, and does not reduce to simple expression
with some collision frequency \delta\sim\nu^{eff}_{e_i}.
