References
http://mathworld.wolfram.com/RubiksCube.html
https://www.rubiks.com/about/the-history-of-the-rubiks-cube
http://www.telegraph.co.uk/technology/google/10840482/Rubiks-cube-invention-40-years-old-and-never-meant-to-be-a-toy.html
http://ruwix.com/the-rubiks-cube/mathematics-of-the-rubiks-cube-permutation-group/
https://www.youtube.com/watch?v=vh0W8E4cNkQ&feature=youtu.be
https://www.youtube.com/watch?v=gVF_XUccMuo&feature=youtu.be