A great introduction to karst can be found on the website of the Missouri Speleological Society

Another good discussion on karst and Ozark water resources can be found in this very goodarticle by Tom Aley.

The website Blue Jewels in the Ozarks: A Beginner's Guide to Missouri Springs has a great deal of good information on Ozark springs with an emphasis on Missouri.

In 1998 Denise Henderson Vaughn wrote a fantastic two part series on karst in the Ozarks for the West Plains Daily Quill. It is available online here

The Ozark Underground Laboratory, in operation since 1973 under Tom Aley, offers both educational and consulting services.