Collaboration, CMS (2019). "Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at = 5.02 TeV". Phys. Lett. B. 797: 134826. arXiv:1810.04602. doi:10.1016/j.physletb.2019.134826. S2CID201698459.
Igor P. Ivanov1, Valeriy G. Serbo2,3, Pengming Zhang4,5, Fate of the Landau-Yang theorem for twisted photons, https://arxiv.org/pdf/1904.12110.pdf "What is actually forbidden is production of a spin-1 particle by such a photon pair"
Collaboration, CMS (2019). "Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at = 5.02 TeV". Phys. Lett. B. 797: 134826. arXiv:1810.04602. doi:10.1016/j.physletb.2019.134826. S2CID201698459.
Bardeen, William A.; Buras, Andrzej J. (1 June 1979). "Higher-order asymptotic-freedom corrections to photon-photon scattering". Physical Review D. 20 (1). American Physical Society (APS): 166–178. Bibcode:1979PhRvD..20..166B. doi:10.1103/physrevd.20.166. ISSN0556-2821.
Bardeen, William A.; Buras, Andrzej J. (1 June 1979). "Higher-order asymptotic-freedom corrections to photon-photon scattering". Physical Review D. 20 (1). American Physical Society (APS): 166–178. Bibcode:1979PhRvD..20..166B. doi:10.1103/physrevd.20.166. ISSN0556-2821.
Collaboration, CMS (2019). "Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at = 5.02 TeV". Phys. Lett. B. 797: 134826. arXiv:1810.04602. doi:10.1016/j.physletb.2019.134826. S2CID201698459.
Bardeen, William A.; Buras, Andrzej J. (1 June 1979). "Higher-order asymptotic-freedom corrections to photon-photon scattering". Physical Review D. 20 (1). American Physical Society (APS): 166–178. Bibcode:1979PhRvD..20..166B. doi:10.1103/physrevd.20.166. ISSN0556-2821.