Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
Ehlers, J. (1998). The Newtonian Limit of General Relativity. In A. K. Richter, & Copernicus Gesellschaft e.V. (Eds.), Understanding Physics (pp. 1-14). Katlenburg-Lindau: Copernicus Gesellschaft.