@incollection {jue:97g, author = {B. J{\"u}ttler}, title = {Sectional curvature preserving interpolation of contour lines}, booktitle = {Curves and Surfaces with Applications in CAGD (A. Le M\'e\-hau\-t\'e (ed.) et al.)}, pages = {203--210}, publisher = {Vanderbilt University Press}, address = {Nashville, TN}, year = {1997} }