Korczak Ziolkowski was a Polish-American sculptor who was invited by Lakota Chief Henry Standing Bear to create the Crazy Horse Memorial.
This website gives a brief comprehensive history of Ziolkowski’s life. It is by no means a complete biography, but it is a good starting point.
The South Dakota State Historical Society's online archives contain resources pertaining to Ziolkowski and the Crazy Horse Monument.
Sulzberger, A. G. “65-Year-Old Monument to Sioux Warrior Still a Work in Progress.” Nation & World, Seattle Times, 17 Mar. 2012, www.seattletimes.com/nation-world/65-year-old-monument-to-sioux-warrior-still-a-work-in-progress/.