Reinforcement Learning: An Introduction, Richard S. Sutton and Andrew G. Barto, 2018 (MIT Press) - Standard textbook for reinforcement learning, with a detailed chapter on policy gradient methods, covering core concepts and the Policy Gradient Theorem.
Foundations of Deep Reinforcement Learning: The Actor-Critic Perspective, Marlos C. Machado, Marc G. Bellemare, and Michael Bowling, 2023 (MIT Press) - Provides a contemporary and rigorous treatment of deep reinforcement learning, offering advanced insights into policy gradient and actor-critic methods.