Measurement of laser intensities approaching 1015 W/cm² with an accuracy of 1%. - Pullen, M. G.; Wallace, W. C.; Laban, D. E.; Palmer, A. J.; Hanne, G. F.; Grum-Grzhimailo, A. N.; Bartschat, K.; Ivanov, I.; Kheifets, A.; Wells, D.; Quiney, H. M.; Tong, X. M.; et al. (Physical Review A: Atomic, Molecular & Optical Physics, 2013)