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Motivated by the recent interest in quantization of black hole area spectrum, we consider the area spectrum of Schwarzschild, BTZ, extremal Reissner-Nordstr\"om, near extremal Schwarzschild-de Sitter, and Kerr black holes. Based on the proposal by Bekenstein and others that the black hole area spectrum is discrete and equally spaced, we implement Kunstatter's method to derive the area spectrum for these black holes. We show that although as Schwarzschild black hole the spectrum is discrete, it is non equispaced in general. In the other hand the reduced phase space quantization is another technique which we discuss here. However there is a discrepancy between the result of the reduced phase space methodology and quasinormal modes approach for area spectrum of some black holes.
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