Quigley, E. D., Peeters, A. G., McCarthy, P. J., Apostoliceanu, M., Hobirk, J., Igochine, V., et al. (2004). Formation criteria and positioning of internal transport barriers in ASDEX Upgrade. Nuclear Fusion, 44, 1189-1196. doi:10.1088/0029-5515/44/11/004.