Where can I find good reference/tutorial on writing Apache modules (in C)?

I've looked all over and can't really find much of anything. I need three basic things:

1. Good API reference
2. Some sort of a tutorial
3. Good architectural overview

I have the module source code and am going through it - but I really don't have much of any context for most of the things its doing.

Any suggestions?

Here is the list of links about apache module development that I found useful:

Apache Tutor

Apache Modules Development and Debugging

libapr(apache portable runtime) programming tutorial

The Apache Modules Book: Application Development with Apache

Mailing list archives

Apache at WebÞing

Writing portable C code with APR

Apache Modeling Project

You can also download the apache source code and experiment with mod_example.