Willingale, L., Mangles, S. P. D., Nilson, P. M., Clarke, R. J., Dangor, A. E., Kaluza, M. C., Karsch, S., Lancaster, K. L.,
Mori, W. B., Najmudin, Z., Schreiber, J., Thomas, A. G. R., Wei, M. S., & Krushelnick, K. (2007).
Comment on "Collimated multi-MeV ion beams from high-intensity laser interactions with underdense plasma".
Physical Review Letters, 98(4):. doi:10.1103/PhysRevLett.98.049504.