1. C. Rovelli, What is observable in classical and quantum gravity? Class. Quantum Grav. 8, 297 (1991)
2. R. Arnowitt, S. Deser, C.W. Misner, in Gravitation: An Introduction to Current Research, vol. 227, ed. by L. Witten (Wiley, New York, 1962)
3. L. Fatibene, M. Ferraris, M. Francaviglia, L. Lusanna, A.D.M. Pseudotensors, Conserved quantities and covariant conservation laws in general relativity. Ann. Phys. 327(6), 1593–1616 (2012). arXiv:1007.4071 [gr-qc]
4. J. Ehlers, F.A.E. Pirani, A. Schild, The Geometry of Free Fall and Light Propagation, in General Relativity, ed. by L.O. Raifeartaigh (Clarendon, Oxford, 1972)
5. S. Capozziello, M.F. De Laurentis, L. Fatibene, M. Ferraris, S. Garruto, Extended cosmologies. SIGMA 12, 006, 16 (2016). arXiv:1509.08008