$ $. Rostislav Ivanovich Grigorchuk is laureate of the Leroy P. Steele Prize of 2015 year. Carpathian Math. Publ. [Internet]. 2014 Dec. 29 [cited 2024 Apr. 28];6(2):399-. Available from: https://journals.pnu.edu.ua/index.php/cmp/article/view/1374