Schmidt, Bernd G. Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
Beig, R., & Schmidt, B. G. (2008). Celestial mechanics of elastic bodies. Mathematische Zeitschrift, 258(2), 381-394. doi:10.1007/s00209-007-0177-5.