Three-photon annihilation of the electron-positron pairs
  Three-photon annihilation of the electron-positron pairs (= $(e^{-}, e^{+})-$pairs) is considered in the electron rest frame. The energy of the incident positron can be arbitrary. The analytical expression for the cross-section of three-photon annihilation of the $(e^{-},e^{+})-$pair has been derived and investigated. 
A.M. Frolov