Chaoha P, Intrakul J, Wichiramala W. Lipschitz retractions onto sphere vs spherical cup in a Hilbert space. TMNA [Internet]. 2018 Nov. 24 [cited 2024 Jul. 3];52(2):677-91. Available from: https://apcz.umk.pl/TMNA/article/view/TMNA.2018.034