Aharonian, F. A., Akhperjanian, A. G., Beilicke, M., Bernlöhr, K., Bojahr, H., Bolz, O., et al. (2003). Is the giant radio galaxy M87 a TeV gamma-ray emitter? Astronomy & Astrophysics, 403(1), L1-L5. doi:10.1051/0004-6361:20030372.