The lecture notes of Julian Schwinger's UCLA course consist of three parts, beginning with an analysis of Stern-Gerlach type experiments. Later the Quantum Acti... » 

The lecture notes of Julian Schwinger's UCLA course consist of three parts, beginning with an analysis of Stern-Gerlach type experiments. Later the Quantum Action Principle (QAP) is accepted as a fundamental principle, and part three consists of instructive applications of the QAP. «