The Schwinger Action Principle and Its Applications to Quantum Mechanics

Schwinger action principle via linear quantum canonical transformations

Space-time-transformation technique in connection with the Schwinger action principle

The action principle in quantum mechanics

THE FEYNMAN PATH INTEGRAL AND SCHWINGER'S ACTION PRINCIPLE

Schwinger’s action principle, supersymmetry and path integrals

Equivalence of Dirac quantization and Schwinger's action principle quantization