Riemann–Hilbert technique scattering analysis of metamaterial-based asymmetric 2D open resonators Piotr M. Kamiński, Richard W. Ziolkowski and Samel Arslanagić EPJ Appl. Metamat., 4 (2017) 10 Published online: 01 December 2017 DOI: 10.1051/epjam/2017007