“…By contrast with the papers [47,48,49,50,51,52], it is assumed that the masses are situated on the boundary rather sparsely, as was assumed in [25,26,27,28,29,30,31,32], when the distance between the masses is substantially greater than their diameter. The distance between the masses is assumed to be equal to ε, the diameter of the masses equal to a ε, where a = a(ε) → 0 as ε → 0, and the density is assumed to be equal to ε −m , m < 2.…”