  A rigorous analytical solution of light propagation in Schwarzschild metric
in post-post Newtonian approximation has been presented in \cite{report1}. In
\cite{report2} it has been asserted that the sum of all those terms which are
of order ${{\cal O} (\frac{m^2}{d^2})}$ and ${{\cal
O}(\frac{m^2}{d_\sigma^2})}$ is not greater than $15/4 \pi \frac{m^2}{d^2}}$
and $15/4 \pi \frac{m^2}{d_\sigma^2}}$, respectively. All these terms can be
neglected on microarcsecond level of accuracy, leading to considerably
simplified analytical transformations of light propagation. In this report, we
give formal mathematical proofs for the inequalities used in the appendices of
\cite{report2}.
