Albert, J.; Ellis, John; Mavromatos, N. E.; Nanopoulos, D. V.; Sakharov, A. S.; Sarkisyan, E. K. G. (2008). "Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope". Physics Letters B. 668 (4): 253–257. arXiv:0708.2889. Bibcode:2008PhLB..668..253M. doi:10.1016/j.physletb.2008.08.053. S2CID5103618.
Albert, J.; Ellis, John; Mavromatos, N. E.; Nanopoulos, D. V.; Sakharov, A. S.; Sarkisyan, E. K. G. (2008). "Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope". Physics Letters B. 668 (4): 253–257. arXiv:0708.2889. Bibcode:2008PhLB..668..253M. doi:10.1016/j.physletb.2008.08.053. S2CID5103618.
Albert, J.; Ellis, John; Mavromatos, N. E.; Nanopoulos, D. V.; Sakharov, A. S.; Sarkisyan, E. K. G. (2008). "Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope". Physics Letters B. 668 (4): 253–257. arXiv:0708.2889. Bibcode:2008PhLB..668..253M. doi:10.1016/j.physletb.2008.08.053. S2CID5103618.
Albert, J.; Ellis, John; Mavromatos, N. E.; Nanopoulos, D. V.; Sakharov, A. S.; Sarkisyan, E. K. G. (2008). "Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope". Physics Letters B. 668 (4): 253–257. arXiv:0708.2889. Bibcode:2008PhLB..668..253M. doi:10.1016/j.physletb.2008.08.053. S2CID5103618.