Pour-El, Marian B., and Ian Richards. “Differentiability Properties of Computable Functions : A Summary”. Acta Cybernetica 4, no. 1 (January 1, 1978): 123-125. Accessed May 2, 2024. https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3171.