The Citadel is an archive of information for George R.R. Martin's A Song of Ice and Fire.
New to the series? Read our spoiler-free review of A Game of Thrones.
The World of Ice and Fire (US, UK) is a source book for A Song of Ice and Fire. Joining Mr. Martin in creating this work are Elio M. García, Jr. and Linda Antonsson (the founders and maintainers of Westeros.org). The book is lavishly illustrated, in-depth guide to the history, geography, cultures, religions, and characters featured in the series.
It was published on October 28, 2014.
The Westeros network consists of several different sites, including a forum and a wiki, for all your A Song of Ice and Fire needs.