S. Tochitsky, R. Narang, C. V. Filip, P. Musumeci, R. Yoder, C. E. Clayton, K. A. Marsh, J. B. Rosenzweig, and C. Joshi, "Beatwave acceleration of 12 MeV electrons to 50 MeV using shaped CO2 laser pulses," in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference, Technical Digest (Optical Society of America, 2003), paper CWN2.