nurbs and curves, info needed

I’d like to find infos about nurbs modeling. I was trying to build a sphere out of a set of 4 bezier patches. The idea was to make a sort of cube with curved surfaces, keeping control points in sync to achieve smooth edges. I managed to draw a tube with bezier, but not a cube. I think I need more control points, but I cannot unterstand how nurbs work. Can you give me some link or hint? (also trimming and everything you know about it)

Check out “The NURBS Book” by Piegl & Tiller.

[This message has been edited by MrToasty (edited 06-29-2000).]