Phase transitions in Sr0.61Ba0.39Nb2O6:Ce3+: II. Linear birefringence studies of spontaneous and precursor polarizationP. Lehnen, W. Kleemann, Th. Woike and R. PankrathEur. Phys. J. B, 14 4 (2000) 633-637DOI: https://doi.org/10.1007/s100510051072