[1] 世界の文字 (2020-08-04T15:52:59.000Z, 2020-10-24T08:15:31.975Z) https://www.chikyukotobamura.org/muse/wr_europa_11.html

[2] IR208cv.PDF - 208.pdf, 2022-11-02T03:16:36.000Z, 2022-12-10T06:00:10.383Z https://itscj.ipsj.or.jp/ir/208.pdf