Magnetic ground state and the spin-state transitions in YBaCo2O5.5 D. P. Kozlenko, Z. Jirák, N. O. Golosova and B. N. Savenko Eur. Phys. J. B, 70 3 (2009) 327-334 Published online: 03 July 2009 DOI: 10.1140/epjb/e2009-00228-x