YOU CHOOSE the books that you need to complete your set.   Buy as many as you want.   The books are all in like new condition EXCEPT that the former owner put the book number on the outer spine of each book.   I have found that the listed order of books sometimes varies, so the numbers may not match exactly the list that you have.  Please check the photo and title of the book for accuracy.   Because it is difficult to set up shipping variances, I am offering discounts ...the more you purchase, the more you save.  Shipping is for 1 pound per book;  think of the money you are saving as applying to the shipping costs. I am hoping it figures out to $5.00 per book plus actual shipping.  Email if you have questions.