  Interplanetary scintillation observations of 48 of the 55 Augusto et al.
(1998) flat spectrum radio sources were carried out at 111 MHz using the
interplanetary scintillation method on the Large Phased Array (LPA) in Russia.
Due to the large size of the LPA beam ($1\degr \times 0.5\degr$) a careful
inspection of all possible confusion sources was made using extant large radio
surveys: 37 of the 48 sources are not confused. We were able to estimate the
scintillating flux densities of 13 sources, getting upper limits for the
remaining 35. Gathering more or improving extant VLBI data on these sources
might significantly improve our results. This proof-of-concept project tells us
that compact ($<1''$) flat spectrum radio sources show strong enough
scintillations at 111 MHz to establish/constrain their spectra (low-frequency
end).
