Sachin Drafts,
http://link.springer.com/article/10.1007%2FBF00348435#page-1 The origin of mathematics - Springer
http://link.springer.com/article/10.1007%2FBF00348435#page-1 The origin of mathematics - Springer
http://link.springer.com/article/10.1007%2FBF00348435#page-1
http://link.springer.com/article/10.1007%2FBF00348435#page-1
http://link.springer.com/article/10.1007%2FBF00348435#page-1