Magnetic properties of the quantum spin- XX diamond chain: the Jordan-Wigner approach T. Verkholyak, J. Strečka, M. Jaščur and J. Richter Eur. Phys. J. B, 80 4 (2011) 433-444 Published online: 30 March 2011 DOI: 10.1140/epjb/e2011-10681-5