Integrability Conditions for Irrotational Dust with a Purely Electric   Weyl Tensor: A Tetrad Analysis
  All spacetimes for an irrotational collisionless fluid with a purely electric Weyl tensor, with spacetime curvature determined by the exact Einstein field equations, are shown to be integrable. These solutions include the relativistic generalisations of the Zeldovich solutions of Newtonian theory. Thus our result shows the consistency of various studies of "silent" universes (where such consistency was assumed rather than proved). 
W.M. Lesame, P.K.S. Dunsby and G.F.R. Ellis