1. For a review and references to the original literature, see J. Polchinski, S. Chaudhuri and C. Johnson, hep-th/9602052.
2. For a review of black hole entropy in string theory and references, see G. Horowitz, gr-qc/9604051.
3. Microscopic origin of the Bekenstein-Hawking entropy
4. L. Susskind, hep-th/9309145
5. Asymptotic level density in heterotic string theory and rotating black holes