Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
Ehlers, J. (1986). On limit relations between and approximate explanations of physical theories. In B. Marcus, & al. (Eds.), Logic, Methodology and Philosophy of Science: Vol VII (pp. 387-403). Amsterdam: Elsevier Science Publ.
