Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
Ehlers, J. (1991). The Newtonian limit of general relativity. In G. Ferrarese (Ed.), Classical Mechanics and Relativity: Relationship and consistency (pp. 95-106). Napoli, Italy: Napoli-Bibliopolis.