Ehlers, Jürgen Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
335128.pdf (Verlagsversion), 2MB
Ehlers, J., & Rudolph, E. (1977). Dynamics of extended bodies in general relativity center-of-mass description and quasirigidity. General Relativity and Gravitation, 8(3), 197-217. doi:10.1007/BF00763547.