Babenko, V. F., Gun’ko, M. S., & Rudenko, A. A. (2014). Optimal Recovery of <em class="a-plus-plus">n</em&gt;-Linear Functionals According to Linear Information. Ukrains’kyi Matematychnyi Zhurnal, 66(7), 884–890. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/2186