KadetsV. М., & Zavarzina, O. O. (2016). Plasticity of the unit ball of $\ell_1$. Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics, 83, 4-9. https://doi.org/10.26565/2221-5646-2016-83-01