@incollection {jue:97d,
 author = {B. J{\"u}ttler},
 title = {Linear convexity conditions for parametric tensor-product {B}\'ezier surface patches},
 booktitle = {The Mathematics of Surfaces, VII (T.N.T. Goodman and R. Martin, eds.)},
 pages = {189--208},
 publisher = {Info. Geom., Winchester},
 year = {1997}
}