[4] Fletcher R.: 
Practical Methods of Optimization. Wiley, 1993. 
MR 0955799[5] Gould N.: 
On practical conditions for the existence and uniqueness of solutions to the general equality quadratic programming problem. Mathematical Programming 32 (1985) 90-99. 
MR 0787745 | 
Zbl 0591.90068[6] Kobza J.: 
Spline recurrences for quartic splines. Acta Univ. Palacki. Olomuc., Fac. rer. nat., Math. 34 (1995), 75-89. 
MR 1447257 | 
Zbl 0854.41011[7] Kobza J.: 
Local representation of quartic splines. Acta Univ. Palacki. Olomuc., Fac. rer. nat., Math. 36 (1997), 63-78. 
MR 1620525[8] Kobza J.: 
Generalized spline smoothing. Folia Fac. Sci. Nat. Univ. Masaryk. Brunensis, Math. 8 (2001), 33-46. 
MR 1843365[9] Kobza J.: 
Quartic splines with minimal norms. Acta Univ. Palacki. Olomuc., Fac. rer. nat., Math. 40 (2001), 83-104. 
MR 1904689[10] Kobza J., Ženčák P.: 
Some algorithms for quartic smoothing splines. Acta Univ. Palacki. Olomuc., Fac. rer. nat., Math. 36 (1997), 79-94. 
MR 1620529 | 
Zbl 0958.41004[12] Reinsch C.: 
Smoothing by spline functions. Numer. Math. 10 (1967), 177-183; 16 (1971) 451-454. 
Zbl 0161.36203[13] Lyche T., Schumaker L. L.: 
Computation of smoothing and interpolating natural splines via local bases. SIAM Jour. Numer. Anal. 10 (1973), 1027-1038. 
MR 0336959 | 
Zbl 0239.65015[15] Vasilenko V. A.: 
Spline Functions. Nauka, Novosibirsk, 1983 (in Russian). 
Zbl 0529.41013[17] Verschinin V. V., Zavjalov J. S., Pavlov N. N.: Extremal properties of Splines and the Smoothing problem. Nauka, Novosibirsk, 1988 (in Russian).
[18] Zavjalov J. S., Kvasov B. I., Miroschnichenko V. L.: Methods of Spline-Functions. Nauka, Moscow, 1985 (in Russian).