1. L. Landau and I. Khalatnikov, ‘‘The Gauge transformation of the Green function for charged particles,’’ Sov. Phys. JETP 2, 69 (1956).
2. E. S. Fradkin, Zh. Eksp. Teor. Fiz. 29, 258261 (1955).
3. M. J. Aslam, A. Bashir, and L. Gutierrez-Guerrero, ‘‘Local Gauge transformation for the quark propagator in an SU(N) Gauge theory,’’ Phys. Rev. D 93, 076001 (2016).
4. P. Dall’Olio, T. de Meerleer, D. Dudal, S. Sorella, and A. Bashir, ‘‘Landau–Khalatnikov–Fradkin transformations for the two loop massless quark propagator,’’ Nucl. Phys. B 973, 115606 (2021).
5. V. M. Villanueva-Sandoval, Y. Concha-Sánchez, L. X. G. Guerrero, and A. Raya, ‘‘On how the scalar propagator transforms covariantly in spinless quantum electrodynamics,’’ J. Phys.: Conf. Ser. 1208, 012001 (2019).