"Wave band gaps in two-dimensional piezoelectric/piezomagnetic phononic crystals" Y.-Z. Wang, F.-M. Li, W.-H. Huang, X. Jiang, Y.-S. Whang, K. Kishimoto, International Journal of Solids and Structures 45 (2008) 4203–4210, DOI: 10.1016/j.ijsolstr.2008.03.001