1. For detailed references on the historical development of the conservation laws of general relativity seeMøller (C. Møller:Ann. of Phys.,4, 347 (1958)) orDavis andMoss (W. R. Davis andM. K. Moss:Nuovo Cimento,38, 1531 (1965)).
2. A. Trautman:Lectures on Relativity, Kings College, London (1959) (unpublished);
3. A. Trautman:Lectures on General Relativity (Englewood Cliffs, N. J., 1964), p. 185.
4. A. Komar:Phys. Rev.,113, 934 (1959).
5. For example, it was shown by Moss and Davis (M. K. Moss andW. R. Davis:Nuovo Cimento (in press)) that the Trautman and Komar expressions were identical for the special case of the Killing vector representing the symmetry property which leads to the angular-momentum conservation law for the Kerr metric.