Simultaneous inference of Jefimenko's and Maxwell's equations from   retardation
  Assuming the idea of retardation as an underlying axiom, we investigate how Jefimenko's and Maxwell's equations can be inferred. In the inference, we begin with the retarded versions of Coulomb's and Biot-Savart's field expression as an incomplete, starting ansatz. By calculating and comparing their divergences, curls, and time derivatives, we improve the ansatz. Thus improved ansatz is further improved through the same procedure and the final ansatz fields are identified with Jefimenko's fields. Our inference of Maxwell's equations is in much the same spirit as the derivation of static differential equations (divergences and curls) from the Coulomb's and Biot-Savart's fields known experimentally without knowing their governing laws of the divergence and curl equations. 
J.-M. Chung