[Zope] Zope Book?

[Shane Graber]

I'm slowly learning Zope and have read through the Zope Book 2.6
that's available from zope.org.  I am also interested in purchasing an
additional book to better understand using Zope.  Does anyone have any
recommendations?  I've been using Zope for a couple months now
(primarily for Plone).  I'm fairly low on the learning curve and would
like to find a good overall book on the subject.  Does anyone have any
recommendations?

Thanks in advance,

Shane Graber