1. Albrecht, H., et al. [ARGUS Collaboration]: Phys. Lett. B 192, 245 (1987)
2. Sirunyan, A.M., et al. [CMS Collaboration]: Phys. Rev. Lett. 120, 231801 (2018)
3. Aabou,d M., et al. [ATLAS Collaboration]: Phys. Lett. B 784, 173 (2018)
4. Tanabashi, M., et al. [Particle Data Group]: Phys. Rev. D 98, 030001 (2018).
http://pdg.lbl.gov/
5. Hou, W.-S.: Phys. Lett. B 296, 179 (1992)