Local dynamics of perovskite ferroelectrics with impuritiesKristoffel, Nikolai; Klopov, MihhailSeventh International Meeting on Ferroelectricity (IMF-7) :August 28-September 1, 1989 : abstracts1989 / p. 76https://www.tandfonline.com/doi/abs/10.1080/07315179008201134