Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
336968.pdf (Publisher version), 2MB
Jordan, P., Ehlers, J., & Kundt, W. (1964). Quantitatives zur Diracschen Schwerkraft-Hypothese. Zeitschrift für Physik A Hadrons and Nuclei, 178(5), 501-541. doi:10.1007/BF01379478.