Sources for the Majumdar-Papapetrou Space-Times
  Einstein's field equations are solved exactly for static charged dust distributions. These solutions generalize the Majumdar Papapetrou metrics. Maxwell's equations lead to the equality of charge and mass densities of the dust distribution. Einstein's equatins reduce to a nonlinear version of Poisson's equation. 
Metin Gurses (Bilkent University)