Nambu-Goldstone modes of the two-dimensional Bose-Einstein condensed magnetoexcitons S.A. Moskalenko, M.A. Liberman, D.W. Snoke, E.V. Dumanov, S.S. Rusu and F. Cerbu Eur. Phys. J. B, 85 10 (2012) 359 Published online: 29 October 2012 DOI: 10.1140/epjb/e2012-30406-6