DE learning resources

[tryptophan]

I'm wondering if someone could point me to some good sites or books to learn more about distance estimation and functions. I have a ton of questions and this forum seems to be the only place that I've found so far to answer them and I am extremely grateful but I don't want to take advantage of this place. I know about the Inigo Iquilez site and have learned a bunch from there but I'm also looking for a more basic understanding.

Could anyone point me in the right direction?

Hopefully in the meantime a few of the experts out there won't mind answering a couple more questions I now have. 

thanks
keith

[Syntopia]

There are not many books or papers on this topic.

I have written an introduction to DE-rendering here, which also lists the resources I know how:
http://blog.hvidtfeldts.net/index.php/2011/06/distance-estimated-3d-fractals-part-i/

[tryptophan]

Awesome that looks like it is exactly what I was looking for. I'll be going thru it for sure. Thanks for the link.

cheers
Keith