The list author says: "I decided to make this list because I wanted to make a list of the materials needed in different programs of study. I decided to make a list of all the books available in Sonlight's P3/4 program. Some prices are better than sonlight's, so this list may be helpful if you're searching for the best prices.
If I was unable to find specific materials, I will mention them. You will need to order the parent's guide from Sonlight itself. I will also choose, in my thinking, good substitutes if I am unable to find exact material."