Must-have book on JTR?

[Harry D]

• Jack the Ripper: The Facts (Paul Begg)
• The Mammoth Book of Jack the Ripper (Maxim Jakubowski)

...would be a good start.

[Harmonica]

First post: I've had a long-running interest in JTR but I'm nowhere near as clued up on the finer details of the case as I'd like to be. What's the must-have/definitive book on Jack the Ripper?

Also wanted to say how much I've enjoyed reading Casebook over the years (albeit without an account)... I dread to think of the amount of time I've spent here, to be honest!