Denisi, V., A. Papa, and M. Rossi. “On the Lorentz-Invariance of the Dyson Series in Theories With Derivative Couplings”. Ukrainian Journal of Physics 66, no. 11 (November 30, 2021): 945. Accessed November 26, 2024. https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2021092.