http://www.agulin.aoyama.ac.jp/mmd/library01/BD90030116/Body/link/n07u0137_144.pdf]
http://www.i-repository.net/contents/asia-u/0000000000652.pdf
Japanese Shyness in classroom
http://ci.nii.ac.jp/els/110009579207.pdf?id=ART0010032133&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1430116696&cp=
http://jalt-publications.org/archive/jj/2003b_JJ.pdf#page=77
http://ir.library.tohoku.ac.jp/re/bitstream/10097/30715/1/KJ00004164855.pdf