M Kenzelmann

Magnetic inversion symmetry breaking and ferroelectricity in TbMnO3.

C. L. Zhang, S. Cheong, A. B. Harris, 2005, Physical review letters.

Direct transition from a disordered to a multiferroic phase on a triangular lattice.

M Jaime, A. B. Harris, Q. Huang, 2007, Physical review letters.