The book
Beta Decay, by C. S. Wu and S. A. Moszkowski, is an excellent book, a refreshing book, highly recommended. Until it was written, a comprehensive knowledge of beta decay could be obtained only by studying many articles written by as many authors using a variety of notations. Now we have the coherent story written without pedantry, mixing experimental fact and theory in just proportion.
Fermi formulated the point-interaction theory of beta decay in 1934. For the next two decades, physicists uncovered the rich phenomena manifest when a neutron or proton was transformed by emitting an electron or positron. Lifetimes and spectra were measured; the classification of decay orders was completed; experiments were carried out on the interaction form and strength.