Passion is a Fashion: the Real Story of The Clash (2004)
Pat Gilbert's definitive, authorized biography of the band is an essential look into the band through historical accounts and interviews with the former members of the band, Strummer, Jones, Simonon, and Headon.
Redemption Song: The Ballad of Joe Strummer (2007)
This nicely written biography of Joe Strummer by Chris Salewicz also reads as an overview of The Clash's music.
The Last Gang in Town: The Story and Myth of The Clash (Second Edition) (2004)
Marcus Gray's unofficial story of The Clash seeks to separate myth from reality, originally published in 1995.