Dragon Prince and Dragon Star trilogies

1. 

   Stronghold (Dragon Star, Book 1)

   Melanie Rawn

2. 

   Sun-Runner's Fire (Dragon Prince, Book 3)

   Melanie Rawn

3. 

   Skybowl

   Melanie Rawn

4. 

   The Dragon Token (Dragon Star, Book 2)

   Melanie Rawn

Book data and covers from Open Library (openlibrary.org).