Scattering states of Dirac particle equation with position-dependent mass under the cusp potential M. Chabab, A. El Batoul, H. Hassanabadi, M. Oulne and S. Zare Eur. Phys. J. Plus, 131 11 (2016) 387 Published online: 07 November 2016 DOI: 10.1140/epjp/i2016-16387-8