Distribution of galaxy groups with at least four member galaxies in Cartesian coordinates (in h^-1 Mpc) in the neighbourhood of the A2142 supercluster. Black filled triangles show groups with at least 50 member galaxies, empty circles groups with 10 ≤ N_gal< 50, and crosses groups with less than ten galaxies. Black filled circles show galaxy groups in the A2142 supercluster with at least four member galaxies. Numbers denote some rich superclusters from Liivamägi et al. (2012) list of superclusters: 1) marks the A2142 supercluster (SCl 001); 2) the Corona Borealis supercluster; 3) the richest supercluster in the Sloan Great Wall; 4) the Bootes supercluster (Liivamägi et al. 2012); and 5) a rich supercluster separated from the A2142 supercluster and the Corona Borealis supercluster by a void. The x, y, and z coordinates are defined as in Park et al. (2007) and in Liivamägi et al. (2012): x = −dsinλ, y = dcosλcosη, and z = dcosλsinη, where d is the comoving distance, and λ and η are the SDSS survey coordinates.