  We study the space distribution of Abell and X-ray selected clusters of
galaxies from the ROSAT Bright Source Catalog, and determine correlation
functions for both cluster samples. On small scales the correlation functions
depend on the cluster environment: clusters in rich superclusters have a larger
correlation length and amplitude than all clusters. On large scales correlation
functions depend on the distribution of superclusters. On these scales
correlation functions for both X-ray and Abell clusters are oscillating with a
period of ~115 h^{-1} Mpc. This property shows the presence of a dominating
scale in the distribution of rich superclusters.
