Physic System? Good resource

i found a site which is very good for people who wanna try program physic systems or need some geometry checking algorithms:

http://www.geometryalgorithms.com/algorithms.htm

or even better from this page below u get links to alot of pages with good resources:
http://www.harveycartel.org/metanet/...tutorialA.html

Looks very useful, thx for link!