Kerr-NUT-de Sitter Metric and Step-by-step Extension Method

The Kerr-NUT-de sitter metric in quasi-Boyer-Lindquest coordinate is derived by using the step-by-step extension method. The extension may be realized in several different paths. For example, one of these paths may be chosen as from Schwarzschild-NUT metric to Schwarzschild- NUT-de Sitter metric and from Schwarzschild-NUT-de Sitter metric to Kerr-NUT-de Sitter metric.