Non-rotationally invariant invisibility cloaks and concentrators of EM Waves G. X. Yu, W. X. Jiang, X. Y. Zhou and T. J. Cui Eur. Phys. J. Appl. Phys., 44 2 (2008) 181-185 Published online: 21 August 2008 DOI: 10.1051/epjap:2008152