http://gigazine.net/news/20171003-3d-crosswalk/

http://www.nikkei-science.com/page/sci_book/bessatu/51215.html

http://www.yuhikaku.co.jp/books/detail/9784641017528

https://www.toben.or.jp/message/libra/libra-2017-10.html

https://www.hokkaido-np.co.jp/article/136594