What are the 15 Guardians of books by Kathryn Lasky in order?

There are actually 16 books in the Guardians of the Book series by Kathryn Lasky, not 15. Here they are in order:

1. The Guardians of the Flory

2. The Guardians of the Flame

3. The Guardians of the Sun

4. The Guardians of the Moon

5. The Guardians of the Stars

6. The Guardians of the Sky

7. The Guardians of the Earth

8. The Guardians of the Sea

9. The Guardians of the Time

10. The Guardians of the Wind

11. The Guardians of the Stone

12. The Guardians of the River

13. The Guardians of the Mountain

14. The Guardians of the Forest

15. The Guardians of the Light

16. The Guardians of the Darkness