Palaniyappan, S., Hegelich, B. M., Wu, H.-C., Jung, D., Gautier, D. C., Yin, L., Albright, B. J., Johnson, R. P., Shimada,
T., Letzring, S., Offermann, D. T., Ren, J., Huang, C., Hörlein, R., Dromey, B., & Shah, J. C. F. R. C. (2012).
Dynamics of relativistic transparency and optical shuttering in expanding overdense plasmas. Nature
Physics, 8, 763-769. doi:10.1038/nphys2390.