• http://www.siggraph.org/education/materials/HyperVis/vistech/volume/surface.htm

• Bloomenthal, “Intro to implicit surfaces”. (edited volume)
• Osher and Fedkiw , “Level set methods and dynamic implicit surfaces” (Springer) - Great book. Also covers some PDE stuff.

• http://www.itk.org/

related; Computer Graphics, Category Geometry