Singmaster, David (1994). "The Utility of Recreational Mathematics". In Guy, Richard K.; Woodrow, Robert E. (eds.). The Lighter Side of Mathematics: Proceedings of the Eugène Strens Memorial Conference on Recreational Mathematics and Its History. Cambridge University Press. p. 340. ISBN088385516X. Singmaster estimates the numbers sold were between 100 and 300 million. His estimate is based on sales of 50 to 100 million legitimate cubes and perhaps a higher number of imitations.
Tom Rokicki (2008). "Twenty-Five Moves Suffice for Rubik's Cube". arXiv:0803.3435 [cs.SC].
Demaine, Erik D.; Demaine, Martin L.; Eisenstat, Sarah; Lubiw, Anna; Winslow, Andrew (2011). "Algorithms for Solving Rubik's Cubes". arXiv:1106.5736v1 [cs.DS].
Singmaster, David (1994). "The Utility of Recreational Mathematics". In Guy, Richard K.; Woodrow, Robert E. (eds.). The Lighter Side of Mathematics: Proceedings of the Eugène Strens Memorial Conference on Recreational Mathematics and Its History. Cambridge University Press. p. 340. ISBN088385516X. Singmaster estimates the numbers sold were between 100 and 300 million. His estimate is based on sales of 50 to 100 million legitimate cubes and perhaps a higher number of imitations.
Davidson, Morley; Dethridge, John; Kociemba, Herbert; Rokicki, Tomas. "God's Number is 20". cube20.org. Retrieved 10 August 2010.
Kunkle, D.; Cooperman, C. (2007). "Twenty-Six Moves Suffice for Rubik's Cube"(PDF). Proceedings of the International Symposium on Symbolic and Algebraic Computation (ISSAC '07). ACM Press.
McKinney, Todd (7 April 2008). "Photo: Blue-bik's cube". The University Record Online. The Regents of the University of Michigan. Archived from the original on 24 February 2021. Retrieved 3 December 2010.
McKinney, Todd (7 April 2008). "Photo: Blue-bik's cube". The University Record Online. The Regents of the University of Michigan. Archived from the original on 24 February 2021. Retrieved 3 December 2010.
