Frolov, P. A., and A. V. Shebeko. “Relativistic Invariance and Mass Renormalization in Quantum Field Theory”. Ukrainian Journal of Physics 59, no. 11 (October 28, 2018): 1060. Accessed April 20, 2024. https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2018547.