Algorithm 46. Determination of an interpolating quadratic spline function E. Neuman (1976) Applicationes Mathematicae
Algorithms 70-71. Determination of a quadratic spline function with given values of the integrals in subintervals E. Neuman (1980) Applicationes Mathematicae
An error analysis for absolute and relative approximation. R.V.M. Zahar, Bacopoulos.A. (1978) Aequationes mathematicae