This chapter deals with everything you'll need to know to get your license, more or less, and you can't be an agent unless you have a license.
You have far more to learn after this, but in order to represent anyone other than yourself in real estate transactions, you need to be a licensed real estate agent or have power of attorney.
These sections are geared towards what you'll need to know for the individual states.
Modern Real Estate Practice, Sixteenth Edition by Filmore W. Galaty, Wellington J. Allaway and Robert C. Kyle, ISBN 0-7931-4428-0
Principles of Real Estate Practice, 5th Edition by Stephen Mettling and David Cusic, ISBN-10: 1500569399. Principles of Real Estate Practice website