A Cellarful of Noise by Brian Epstein, Martin Lewis.

In My Life: The Brian Epstein Story by Debbie Geller, Anthony Wall (Editor).

Those Were the Days: An Unofficial History of the Beatles' Apple Organization 1967-2002 by Stefan Granados (Informative and well-written.  Highly recommended book by beatlemoney.com)

MBE: The Official Brian Epstein Web Site

beatlesagain.com: Brian Epstein Portfolio

aboutthebeatles: Brian Epstein Biography

beatles.net: Brian Epstein