Kirk, John G. Division Prof. Dr. Werner Hofmann, MPI for Nuclear Physics, Max Planck Society;
Maccione, L., Liberati, S., Celotti, A., & Kirk, J. G. (2007). New constraints on Planck-scale Lorentz Violation in QED from the Crab Nebula. Journal of Cosmology and Astroparticle Physics, 10: 013, pp. 1-24. doi:10.1088/1475-7516/2007/10/013.