@incollection {jue:98g,
 author = {B. J\"u{}ttler},
 title = {Construction and modification of convex parametric spline curves and surfaces},
 booktitle = {Creating fair and shape-preserving curves and surfaces (H. Nowacki and P. Kaklis, eds.)},
 pages = {219--229},
 publisher = {Teubner},
 address = {Stuttgart},
 year = {1998}
}