"The volume is exemplary documented and annotated. It makes up an essential source not only for the history of theoretical physics but also for the history of twentieth-century culture in general." (H. Kragh, Centaurus, 2000) "The correspondence offers comprehensive insight into the state of the theoretical concepts of quantum field theory before the introduction of the theory of electro-weak interaction and immediately before the proof of parity non-conservation during radioactive decay. In retrospect, the discussions between Pauli and Heisenberg, which initially appeared to lead to a joint unification formula, are an important chapter in the history of physics." (Mathematical Reviews 2001h)