Reinforcement Learning: An Introduction, Richard S. Sutton and Andrew G. Barto, 2018 (The MIT Press) - The standard textbook on Reinforcement Learning, providing a detailed explanation of the agent-environment interface, the components of the interaction loop, and foundational concepts.
Reinforcement Learning Lecture 1: Introduction to Reinforcement Learning, David Silver, 2015University College London (UCL) Course Materials - An introductory lecture from a prominent course that clearly outlines the Reinforcement Learning problem, including the agent-environment interaction model.
Markov Decision Processes (MDPs), Pieter Abbeel, Dan Klein, 2017UC Berkeley CS188 Course Materials (University of California, Berkeley) - Lecture notes providing a concise explanation of Markov Decision Processes, which formally model the sequential decision-making process described by the RL interaction loop.