Koch, K., Kuzian, R. O., Koepernik, K., Kondakova, I. V., & Rosner, H. (2009). Analysis of the electric field gradient in the perovskites SrTiO3 and BaTiO3: Density functional and model calculations. Physical Review B, 80:, pp. 125113-1-125113-9. doi:10.1103/PhysRevB.80.125113.