Andersson, Lars Geometric Analysis and Gravitation, AEI-Golm, MPI for Gravitational Physics, Max Planck Society;
1402.6252.pdf (Preprint), 453KB
CQG_31_13_135015.pdf (Any fulltext), 541KB
Andersson, L., Bäckdahl, T., & Blue, P. (2014). Second order symmetry operators. Classical and quantum gravity, 31: 135015. doi:10.1088/0264-9381/31/13/135015.