The NURBS Book (Monographs in Visual Communication)
"Piegl and Tiller offer an excellent source of information on NURBS (nonuniform rational B-spines), which fills a very large gap in the technical literature related to CAD/CAM/CAE.  It is written for the average engineer with elementary knowledge of college mathematics and computing.  It would be very useful to students, teachers, and designers of geometric modeling systems.  A well-presented work, with abundant computer-generated figures."  --Choice