The discussion centers on recommendations for textbooks in quantum mechanics and mathematical physics, particularly those that include Green's functions. A notable suggestion is "Mathematics of Classical and Quantum Physics" by Byron and Fuller, praised for its affordability as a Dover publication. For mathematical physics, "Mathematical Physics" by S. Hassani is recommended, although it focuses on mathematics for physicists rather than a deeper mathematical treatment. Another suggestion is "Quantum Mechanics for Mathematicians" by Leon A. Takhtajan, which is used in a mathematical foundation course. The conversation highlights the importance of reviewing textbooks before purchase due to their high cost and varying suitability. Additionally, "Mathematical Methods of Classical Mechanics" by Arnold and "Mathematics for Physics and Physicists" by Walter Appel are mentioned as valuable resources, with the latter offering a more mathematical perspective.