Although a wealth of rock encyclopedias exist and nearly all have a small section covering Mott the Hoople and Ian Hunter, there are very few books dedicated to them. It is impossible to do Mott's or Ian's careers justice in only a handful of paragraphs and, sadly, most of these encyclopedias contain errors (mostly minor, but one or two contain major "howlers").
Of course, there is Willard Manus' novel Mott The Hoople, which inspired the name, from 1966. Sadly, it is out of print, although a few copies are still available from Mr Manus himself. Then there is Ian's famous Diary Of A Rock 'n' Roll Star, chronicling Mott's 1972 American tour and now back in print. More recently there has been Phil Cato's disappointing and entirely derivative book. And now there is Campbell Devine's Official Biography, which is the definitive work on the subject which gets an unqualified buy it recommendation from me. And hot on the heels of that, there is the newly-formed Mott The Hoople Appreciation Society.
Finally, there are the excellent Outsider and Just A Buzz fanzines, put out by long-time fans Sven Gusevik and Justin Purington respectively. Both also get an unqualified buy it recommendation from me.