There are three required books, and you will see all of them in the first lesson of the course after you have enrolled. The books go along with the course so it's recommended that you don't read ahead. They are readily available, new and used, on Amazon and other online retail sites. It's also possible that your local library will have them.
You can also search our CourseCareers community discord channel to find where other members have purchased their books. Some students have posted links to audio books and PDF books.