There have been scores of books about (and by) The Beatles. Among the best:

In His Own Write / A Spaniard in the Works (by John Lennon)
The Beatles Illustrated Lyrics
The Beatles: An Illustrated Record
The Beatles (A Reference and Value Guide)
Beatletoons: The Real Story Behind the Cartoon Beatles
A Hard Day's Write (The Stories Behind Every Beatles' Song)
The Beatles Anthology (by The Beatles)

Does anyone care to recommend any others?

Tell Me Why - Tim Riley (a song-by-song analysis of their work)