FERROELECTRIC PHASE TRANSITIONS IN IONIC CONDUCTORS BASED ON BISMUTH VADANATE Статья Politova E.D., Fortal'nova E.A., Kaleva G.M., Mosunov A.V., Andronova L.I., Andropova S.A., Safronenko M.G., Venskovskii N.U. Physics of the Solid State. Том 51. 2009. С. 1443-1448