Are Clusters as Indicators of the Cosmic Ray Anisotropy ?
  The clusters (doublets) in ultrahigh energy cosmic rays are considered based on Yakutsk and AGASA extensive air shower array data. The problem of cluster origin is discussed. It is found that arrival directions of the clusters can point to a cosmic ray anisotropy. As a result of analysis of clusters, the conclusion on composition and origin of ultrahigh energy cosmic rays has been made. 
A.A.Mikhailov, N.N.Efremov