Gilli, M. and Grosse, S. and Schumann, E. (2010) Calibrating the Nelson-Siegel-Svensson model, COMISEF Working Paper Series No. 031.
http://comisef.eu/files/wps031.pdf
Gilli, M., Maringer, D. and Schumann, E. (2019) Numerical
Methods and Optimization in Finance. 2nd edition. Elsevier.
https://www.elsevier.com/books/numerical-methods-and-optimization-in-finance/gilli/978-0-12-815065-8
Gilli, M. and Schumann, E. (2010) A Note on ‘Good’ Starting Values in Numerical Optimisation,
COMISEF Working Paper Series No. 044. http://comisef.eu/files/wps044.pdf
Nelson, C.R. and Siegel, A.F. (1987) Parsimonious Modeling of Yield Curves. Journal of Business, 60(4), pp. 473--489.
Schumann, E. (2019) Financial Optimisation with R (NMOF Manual).
http://enricoschumann.net/NMOF.htm#NMOFmanual
Svensson, L.E. (1994) Estimating and Interpreting Forward Interest Rates: Sweden 1992--1994. IMF Working Paper 94/114.