X(3872) and its heavy quark spin symmetry partners in QCD sum rules Halil Mutuk, Yasemin Saraç, Hasan Gümüş and Altuğ Özpineci Eur. Phys. J. C, 78 11 (2018) 904 Published online: 08 November 2018 DOI: 10.1140/epjc/s10052-018-6382-z