http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/53829/1/AA12219452_119_09.pdf

http://ci.nii.ac.jp/els/110007153146.pdf?id=ART0009105715&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1443920041&cp=

http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/15697/1/47%285%29_p430-447.pdf

https://icu.repo.nii.ac.jp/?action=pages_view_main&active_action=repository_view_main_item_detail&item_id=3160&item_no=1&page_id=13&block_id=17

http://ci.nii.ac.jp/els/110001000399.pdf?id=ART0001180744&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1443915844&cp=

https://www.jstage.jst.go.jp/article/jalp1953/2002/0/2002_0_29/_pdf 

http://ci.nii.ac.jp/els/110003144723.pdf?id=ART0003553566&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1441966019&cp=