  We have used integral two-point spatial correlation function and its second
derivative to analyze the distribution of quasars in three very deep surveys
published in the literature. Statistically significant ($\sim 2-3\sigma $)
correlations were found at scales of $\sim 50-100h^{-1}$ Mpc in all of the
analyzed surveys. We have used the friends-of-friends cluster analysis to show
that these correlations can be explained by the presence of relatively small
quasar clusters (3-6 objects) which may possibly belong to larger structures
such as Large Quasar Groups found in the bigger surveys. The sizes of these
clusters along the redshift direction and distances between them are similar to
those for structures found recently in studies of CIV absorption systems. These
results present further evidence for the existence of large-scale structures at
redshifts $z\sim 1-2$.
