Entanglement in the linear-chain Heisenberg antiferromagnet Cu(C4H4N2)(NO3)2Josep Batle, Ahmed Farouk, Majid Alkhambashi and Soliman AbdallaEur. Phys. J. B, 90 3 (2017) 49DOI: https://doi.org/10.1140/epjb/e2017-80004-1