Causal perturbation theory approach to Yukawa’s model O. A. Acevedo, J. Beltrán, B. M. Pimentel and D. E. Soto Eur. Phys. J. Plus, 136 9 (2021) 895 Published online: 01 September 2021 DOI: 10.1140/epjp/s13360-021-01805-1