David’s extensive and beautifully organized collection of audio teachings can be found at acim.me. The reserve is divided into 3 sections: the Text, the Workbook, and also the Handbook for Instructors. All are overflowing with useful spiritual knowledge. Still the "engine room" in the Course is its day-to-day Workbook classes, https://awakening-mind.org/resources/a-course-in-miracles/