  The problem of long-range correlations of particles produced in high- energy
collisions is discussed. Long-range correlations involve large groups of
particles. Among them are, e.g., those correlations which lead to ring-like and
elliptic flow shapes of individual high-multiplicity events in the
polar+azimuthal angles plane. The \w method of \an which allows to disentangle
various patterns has been proposed and applied to some central lead-lead
collisions at energy 158 GeV per nucleon. Previous attempts to find out the
ring-like correlations and recent results on \w \an of high- energy nuclei
interactions are reviewed.
