Microscopic spin-wave theory for yttrium-iron garnet films A. Kreisel, F. Sauli, L. Bartosch and P. Kopietz Eur. Phys. J. B, 71 1 (2009) 59-68 Published online: 11 August 2009 DOI: 10.1140/epjb/e2009-00279-y