You may want to look up the books used in college courses so you can study the book and learn the material on your own.
First you will need to know what the course numbers are for a certain major. Lets look at the Computer Science major at Iowa State University
Here is a link to all of the majors offered at Iowa State:
http://catalog.iastate.edu/azcourses/
Here is the link for all of the current courses in Iowa State’s Com Sci major:
Now we need to look up the book. Here is the link to search the Iowa State book store for the book. Go ahead and ‘Search by Course’
https://www.isubookstore.com/SelectTermDept?reg=8
You can add all of the courses you are interested in and then click on ‘View My Materials’