1. L. Bombelli, R.K. Koul, J. Lee and R.D. Sorkin, A quantum source of entropy for black holes, Phys. Rev. D 34 (1986) 373 [ INSPIRE ].
2. M. Srednicki, Entropy and area, Phys. Rev. Lett. 71 (1993) 666 [ hep-th/9303048 ] [ INSPIRE ].
3. L. Susskind and J. Uglum, Black hole entropy in canonical quantum gravity and superstring theory, Phys. Rev. D 50 (1994) 2700 [ hep-th/9401070 ] [ INSPIRE ].
4. C.G. Callan Jr. and F. Wilczek, On geometric entropy, Phys. Lett. B 333 (1994) 55 [ hep-th/9401072 ] [ INSPIRE ].
5. P. Calabrese and J.L. Cardy, Entanglement entropy and quantum field theory, J. Stat. Mech. 0406 (2004) P06002 [ hep-th/0405152 ] [ INSPIRE ].