LHCb collaboration, Aaij, R., Abellán Beteta, C., Ackernley, T., Adeva, B., Adinolfi, M., et al. (2020). Search for the Rare Decays Bs0→e+e- and B0→e+e-. Physical Review Letters, 124(21): 211802. doi:10.1103/PhysRevLett.124.122002.