Keitel, Christoph H. Division Prof. Dr. Christoph H. Keitel, MPI for Nuclear Physics, Max Planck Society;
Kurizki, G., Scully, M. O., & Keitel, C. H. (1993). Free-electron lasing without inversion by interference of momentum states. Physical Review Letters, 70(10), 1433-1436. doi:10.1103/PhysRevLett.70.1433.