2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51387Given a relativistic two-point Green's function for a spinor system with spherical symmetry we show how to obtain another in the same class by extended point canonical transformations (XPCT).The work in this note was motivated by a problem posed by Eric-Olivier Le BigotHigh Energy Physics - Theorytext