Scattering states of Dirac particle equation with position-dependent mass under the cusp potentialM. Chabab, A. El Batoul, H. Hassanabadi, M. Oulne and S. ZareEur. Phys. J. Plus, 131 11 (2016) 387DOI: https://doi.org/10.1140/epjp/i2016-16387-8