1. See, for example, H.H. Braun, in: Proceedings of the 2012 International Conference on Particle Acceleration, New Orleans, LA, USA, 2012, 4180.
2. See, for example, N. Nakamura, in: Proceedings of the 2012 International Conference on Particle Acceleration, New Orleans, LA, USA, 2012, 1040.
3. Operation of a free-electron laser from the extreme ultraviolet to the water window
4. First lasing and operation of an ångstrom-wavelength free-electron laser