[Sigia-l] SAP Books

[Peter VanDijck]

Hi all,
I have been working with the SAP Portals product for a while, but I'm
still finding it hard to really understand the whole SAP architecture
and all its various peculiarities. There is little information out there
that explains SAP at the level that an IA needs. Most of the books I see
seem to be either purely technical (ie. for programmers) or on the
business level. 

Can anyone recommend an SAP book (or other resource) that explains
things like how SAP Portals deals with personalization, how the overall
SAP architecture works, what the various different types of interfaces
mean, their TREX product and how it fits in, and so on.

If not, any tips on how to get this information are appreciated.

Thanks!
Cheers,
Peter