Git Basics - Recording Changes to Your Repository, Scott Chacon, Ben Straub, 2014 (Apress) - This chapter from the official Git documentation provides a fundamental explanation of the Git workflow, including the working directory, staging area, and repository, along with file states and key commands like git add and git commit.
Pro Git, Scott Chacon, Ben Straub, 2014 (Apress) - The comprehensive and authoritative book on Git, which covers the core concepts of Git's architecture, including the workflow of modifying, staging, and committing changes, in great detail.