It is a nice article.

Haga's theorem are there,
http://www.origami.gr.jp/Archives/People/CAGE_/divide/02-e.html
Mathematics of paper folding,
http://en.wikipedia.org/wiki/Mathematics_of_paper_folding#cite_note-12

Haga's book, we can get by Amazon,
ORIGAMICS: MATHEMATICAL EXPOLORATIONS THROUGH PAPER FOLDING

CAPTCHA
This question is for testing whether you are a human visitor and to prevent automated spam submissions.