Typo on p.16: left Bezier patch of the characteristic map has
a number of transposed entries associated with cn.
The patch should equal the of lower right patch with the sign of the 2nd coordinate flipped.
Curves and Surfaces in Geometric Design,
Pierre Jean Laurent, Alain Le Méhauté, Larry L. Schumaker (eds.),
International Conference on Curves and Surfaces in Geometric Design,
For general modeling I recommend C^1-surface splines.
Surfaces...bicubics is older, uses more patches,
uses more complicated formulas, does not prove the convex hull property.
It is however the first of this type of construction.