Elets, L. V., and P. A. Masharov. “On One Extremal Problem of Pompeiu Sets”.
Ukrains’kyi Matematychnyi Zhurnal
61, no. 1 (January 25, 2009): 61–72. Accessed April 27, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/3001
.