Gilsinn, D.
and Lavery, J.
(2002),
Shape-Preserving, Multi-Scale Fitting of Bivariate Data by Cubic L<sub>1</sub> Smoothing Splines, Journal of Approximation Theory, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=150830
(Accessed April 18, 2025)