Knödlseder, J., Jean, P., Lonjou, V., Weidenspointner, G., Guessoum, N., Gillard, W., et al. (2005). The all-sky distribution of 511 keV electron-positron annihilation emission. Astronomy & Astrophysics, 441(2), 513-532. doi:10.1051/0004-6361:20042063.