Problem of quantum numbers of lepton sector

A unique approach to describing wave equations of stable and unstable leptons is developed. Its algorithm is based on four initial principles which are the necessary and sufficient conditions for finding equations. The main advantage and value of the proposed method is that it provides a description and enumeration of all possible types of free equations for stable and unstable leptons in the framework of the homogeneous Lorentz group based on the unified approach without the use of the Lagrange formalism.