[Zope] Docs relating to apps server [Q]

Hi! I will have to give an internal presentation about application servers. I am a software developer and I have to explain what is actually an application server to a web-development group (mainly graphic desginers, html markets and GUI designers). I have to make clear why an app server is best than continue to develop traditional CGI-ish web sites. I can think a lot of reasons (code reusability, delegation, etc) but I would like to have some docs to backup my statements. Can anyone point me to some docs? Some publications? Thanks a lot Cheers, ZBruno :-)