Entanglement in the linear-chain Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2 Josep Batle, Ahmed Farouk, Majid Alkhambashi and Soliman Abdalla Eur. Phys. J. B, 90 3 (2017) 49 Published online: 15 March 2017 DOI: 10.1140/epjb/e2017-80004-1