Semiclassical black hole states and entropy

We discuss semiclassical states in quantum gravity corresponding to Schwarzschild as well as Reissner-Nordstrom black holes. We show that reduced quantization of these models is equivalent to Wheeler-DeWitt quantization with a particular factor ordering. We then demonstrate how the entropy of black holes can be consistently calculated from these states. While this leads to the Bekenstein-Hawking entropy in the Schwarzschild and non-extreme Reissner-Nordstrom cases, the entropy for the extreme Reissner-Nordstrom case turns our to be zero.