FEYNMAN OFFERS ADVICE AND ENCOURAGEMENT FOR A SCIENTIFIC ENDEAVOR. More about Autograph Letter Signed [ALS

FIRST EDITION IN ORIGINAL WRAPPERS of Feynman’s paper providing a rigorous justification and proof for his famous “Feynman diagrams” and “Feynman rules”. More about Mathematical Formulation of the Quantum Theory of Electromagnetic Interaction

First edition, first printing, of Feynman's path integral formalism, his revolutionary approach to solving the fundamental equations of quantum mechanics and the basis for his later famous formulations of "Feynman rules" and "Feynman diagrams" More about Space-Time Approach to Non-Relativistic Quantum Mechanics