Núñez Yépez, H., A. Salas Brito, ., and C. Vargas. “Electric and Magnetic Four-Vectors in Classical Electrodynamics”. Revista Mexicana De Física, vol. 34, no. 4, Jan. 1987, pp. 636-44, https://rmf.smf.mx/ojs/index.php/rmf/article/view/2022.