The Soviet statistical authorities first published an input-output table (for 1959) in their statistical yearbook of 1960; they had recommenced issuing their general abstracts in 1956—a direct consequence of, and only a few weeks after, the Twentieth Party Congress—following a lapse of nearly two decades. The input-output table as published was incomplete, and the coverage of the annual abstracts has only modestly increased since it reached its present size in 1958. The lacunae have presented a challenge to Western economists in three respects. The first difficulty is in reconstructing a series only part of which has been officially published. The best example of this lies in the reconstruction of input-output tables described below. The second challenge is to estimate aggregates (including the filling in of time series) which the statistical authorities of the USSR choose either not to make public or to publish in nontabular form.