Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
S0218271806008966.pdf (Publisher version), 134KB
Ehlers, J. (2006). A. K. Raychaudhuri and his equation. International Journal of Modern Physics D, 15(10), 1573-1580.