1. H.F. Kristiansen, Modified Newtonian Gravity and the theory of
Electrograviotisme, Roskilde University Digital Archive, 2-May-2008,
http://rudar.ruc.dk/handle/1800/3093
2. W.M. Herdy, Electrodynamics of Maxwell-Proca and the massive photon
(in Portuguese), (Centro Brasiliero de Pesquisas Fisicas, Rio de Janeiro
2010)
3. Chris Vuille, arXiv:1610.03703v1 [physics.gen-ph] 2016.