Dirac's published a famous textbook known as the "Principles of Quantum Mechanics" (1930 AD). This book introduced the widely used delta function and [[bracket notation]]. Inspired in part by this book, the well known athienst physicist Richard Feynman later proposed a path integral formulation of quantum mechanics in 1948 AD. | Dirac's published a famous textbook known as the "Principles of Quantum Mechanics" (1930 AD). This book introduced the widely used delta function and [[bracket notation]]. Inspired in part by this book, the well known athienst physicist Richard Feynman later proposed a path integral formulation of quantum mechanics in 1948 AD. |