Polarization diagram theory was developed for various situations. These were the 2-dipole problem, the case of distributed pair centers, and the case of dipoles in hexagonal-type crystals. The results of the calculations were used to evaluate the symmetry of, and to propose models for, complex centers.

S.S.Ostapenko, M.K.Sheinkman: Materials Science Forum, 1992, 83-87, 1127-34