Meško, Ivan. “Piecewise Linear Functions in \(\mathbb{R}^3\)”. Anal. Numér. Théor. Approx. 15, no. 1 (February 1, 1986): 49–55. Accessed May 17, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1986-vol15-no1-art7.