A new phase in ferroelectric oxides: The phase of charge transfer vibronic excitonsV. S. Vikhnin, R. I. Eglitis, S. E. Kapphan, E. A. Kotomin and G. BorstelEurophys. Lett., 56 5 (2001) 702-708DOI: https://doi.org/10.1209/epl/i2001-00577-6