Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., et al. (2010). A population of gamma-ray emitting globular clusters seen with the Fermi large area telescope. Astronomy & Astrophysics, 524: A75, pp. 1-11. doi:10.1051/0004-6361/201014458.