Find books by purchase date

I have a fairly large library of books, and I developed a system to keep track of books. As new books were purchased, they appeared on top of my Library View with a New banner over the cover. As I read them, I would file the books by author. In this manner I could always find things. Recently, iBooks has begun to create groups for me. When I purchase a book, I am never quite sure where it goes now. This is further complicated when I buy something before release. On the release date it downloads and I get a notification. However, I don't always know where it is. These automatic groups are created by Author(s). This means authors like Patterson and Cussler are in multiple groups, due to different writing partners. When I buy the book, I do not record everything and therefore I am having a hard time finding the books. Is there a way to organize a book view by purchase date? Alternatively, is there a view for New, Unread books?