Gravitomagnetism and Angular Momenta of Black-Holes
  We review the energy contents formulae of Kerr-Newman black-holes, where gravitomagnetic energy term comes to play(Berman, 2006; 2006a; 2004). Then, we obtain the angular momenta formulae, which include the gravitomagnetic effect. Three theorems can be enunciated: (1) No black-hole has its energy confined to its interior; (2) Rotating black-holes do not have confined angular momenta; (3) The energy density of a black-hole is not confined to its interior. The difference between our calculation and previous ones by Virbhadra(1990, 1990a, 1990b), and Aguirregabiria et al.(1996), lies in the fact that we include a term responsible for the self-gravitational energy, while the cited authors discarded such effect, which appears in the static black hole energy calculation. 
Marcelo Samuel Berman