For a thorough understanding of the Lamb shift and its implications in quantum electrodynamics (QED), two highly recommended texts are Landau and Lifshitz's "Course on Theoretical Physics, Vol 4" and S. Weinberg's "Quantum Theory of Fields, Vol. 1." While Landau and Lifshitz provide a solid application-focused treatment of the topic, they are noted for their older methods, which may not be ideal for beginners in QED. Weinberg's work is also recognized for its comprehensive approach to quantum field theory, making it a valuable resource for those studying the Lamb shift and its effects on atomic energy levels.