Operational Quantum Theory II: Relativistic Structures, Vol. 2 Book

An interesting collection of topics in the field, though far from a comprehensive or even pedagogical treatment. Very heavy on the operator theory perspective, which sets this book apart from other popular treatments like Birrell & Davies. Though a useful perspective, this approach really only provides the garnish to the meat and potatoes of more mainstream textbooks. Section 7, on particle production in the expanding universe, is however perhaps the cleanest take on this topic in the literature.