'Staying Up' by Rick Gekoski is great, and I'm currently reading 'Ghosts of a Vanished Stadium-Coventry City at Highfield Road' by Jim Brown, which is really interesting. I'd recommend both. I've also read 'Ernie Hunt's Sideburns' which is a collection of random City stories by supporters and 'Sky Blue Heaven' is good, infact volume 2 is on my wish list!
Are you looking for a history of the club? The best is COVENTRY CITY: A COMPLETE RECORD 1883-1991 compiled by Rod Dean. Big hardback. But its expensive at over £30 +.
COVENTRY CITY: A HISTORY IN 50 MATCHES by Jonathan Strange is good. And much cheaper. £12+