... Gaseous discs in NGC 252 and in NGC 4513 have decoupled kinematics, and the ionized gas of their rings is certainly excited by young stars. ... Two other, quite isolated S0 galaxies with the UV rings, IC 522 and NGC 446, demonstrate the shock-dominated gas excitation in the UV-detected rings, so their rings may probably have impact origin. ... NGC 4513. ... The UV rings in isolated galaxies IC 522 and NGC 446 may represent the consequences of central impact by a satellite from a highly inclined...