1. Björck, A.: Numerical Methods for Least Squares Problems, Philadelphia: SIAM, 1996.
2. Butler, J. H. and Montzka, S. A.: The NOAA Annual Greenhouse Gas Index (AGGI), National Oceanic and Atmospheric Administration Earth System Research Laboratory, Global Monitoring Division, U.S. Department of Commerce, available at: http://esrl.noaa.gov/gmd/aggi/aggi.html, last access: July 2016.
3. Cox, M. G.: The numerical evaluation of B-splines, J. Inst. Math. Appl., 10, 134–149, 1972.
4. Cox, M. G.: Algorithms for spline curves and surfaces, in: Fundamental Developments of Computer-Aided Geometric Modelling, edited by: Piegl, L., London: Academic, 51–76, 1993.
5. de Boor, C.: A Practical Guide to Splines, New York: Springer, 1978.