1. S.S. Schweber, An Introduction to Relativistic Quantum Field Theory (Harper and Row, New York, 1962). The topic of the Dirac equation is found in any textbook of quantum mechanics dealing with relativistic equations, but the present book contains a very clear and complete discussion of it
2. F. Mandl, G. Shaw, Quantum Field Theory (Wiley, London, 2010). An excellent book to start the study of quantum field theory
3. A.I. Akhiezer, V.B. Berestetskii, Quantum Electrodynamics (Interscience, Wiley, New York, 1965). This is a classic text of quantum electrodynamics
4. R.P. Feynman, Quantum Electrodynamics (W.A. Benjamin, New York, 1961). Contains a very original treatment of the topic, as usual in Feynman’s books
5. S.S. Schweber, QED and the Men Who Made It: Dyson, Feynman, Schwinger, and Tomonaga (Princeton University Press, Princeton, 1994). A remarkable book on the history of quantum electrodynamics, including all the original derivations and references