Non-Bragg bandgaps of quasi-one-dimensional comb-like structures composed of positive and negative index materialsL. W. Zhang, Y. W. Zhang, L. He and Z. G. WangEur. Phys. J. D, 55 1 (2009) 155-159DOI: https://doi.org/10.1140/epjd/e2009-00204-8