Distribution of groups with at least four member galaxies in superclusters in x,y, and z coordinates (in h^-1 Mpc, grey dots). Black filled circles denote clusters with at least 50 member galaxies in superclusters, dark grey empty circles those clusters with at least 50 member galaxies which are not located in superclusters. Numbers are ID numbers of superclusters with at least 500 member galaxies.