B. Hidding, G.G. Manahan, G. McKendrick. D.A. Jaroszynski, Z.-M. Sheng, G.H. Welsh, S.M. Wiggins, N. Bourgeois, J. Cowley, S. Hooker, O. Karger, G. Wittig, A. Knetsch, J.B. Rosenzweig, Y. Xi, A. Deng, D.L. Bruhwiler and J. Smith, “Attosecond electron bunches from underdense plasma photocathodes by simultaneous space-time focused lasers,” presented at the Advanced Accelerator Concepts Workshop (San Jose, July 2014).