In celebration of the 20th anniversary of George R. R. Martin’s best-selling book, A Game of Thrones: Enhanced Edition is available exclusively on Apple's iBooks. The enhanced edition of Book One, "A Game of Thrones," comes out Thursday exclusively through Apple's iBooks. It was first published 20 years ago. Books Two through Five to follow in the coming months.

All volumes made in collaboration with Apple will include interactive character maps, glossaries, annotations, house summaries and other features.

The Appendix section includes all 92 house sigils, providing information about symbolism, house seat, region and allegiances.

Each book also will include an excerpt from Martin's ever-awaited Book Six, "The Winds of Winter," for which a release date is not set.

A Game of Thrones: Enhanced Edition is available exclusively on iBooks in English for $8.99. Enhanced Editions of Books Two through Five in George R. R. Martin’s A Song of Ice and Fire series are available for pre-order ($11.99).