Gavrilov S. P. Particle scattering and vacuum instability by exponential steps / S. P. Gavrilov, D. M. Gitman, A. A. Shishmarev // Physical Review D. 2017. Vol. 96, № 9. P. 096020-1-096020-17. URL: http://vital.lib.tsu.ru/vital/access/manager/Repository/vtls:000644257