Doneux, J., Saint Aubin, Y., & Vinet, L. (1982). Matter-coupled Yang-Mills system in Minkowski space. II. Invariant solutions in the presence of Dirac spinor fields. Physical Review D, Particles, Fields, Gravitation and Cosmology, 25, 484. https://doi.org/10.1103/PhysRevD.25.484 (Original work published 1982)