Serdyuk, A. S., and O. I. Stepanets. “On the Existence of Interpolating $SK$-Splines”.
Ukrains’kyi Matematychnyi Zhurnal
, vol. 46, no. 11, Nov. 1994, pp. 1546–1553,
https://umj.imath.kiev.ua/index.php/umj/article/view/5593
.