The study of Goldstone modes in ν = 2 bilayer quantum Hall systems Y. Hama, Y. Hidaka, G. Tsitsishvili and Z.F. Ezawa Eur. Phys. J. B, 85 11 (2012) 368 Published online: 14 November 2012 DOI: 10.1140/epjb/e2012-30559-2