Reinforcement Learning: An Introduction, Richard S. Sutton and Andrew G. Barto, 2018 (MIT Press) - A comprehensive and authoritative textbook covering the foundations of reinforcement learning, including detailed explanations of policy gradient, value-based methods, and actor-critic architectures.
Policy Gradients and Actor-Critic, Sergey Levine, 2021 - Lecture notes from a leading university course on deep reinforcement learning, offering a clear and concise academic explanation of policy gradient methods and the fundamental principles of actor-critic algorithms.