1. Akarenga, “Hokkaido’s History, Culture and Nature” in Akarenga portal site of Hokkaido’s History and Culture [downloaded on 1 Jan 2018], available at
https://www.akarenga-h.jp/en/hokkaido/kaitaku/k-04/
2. Allen, Matthew, "Undermining the occupation: women coalminers in 1940s Japan" dated 2010 in University of Wollongong Research Online Faculty of Arts Papers (Archive) Portal Journal of Multidisciplinary International Studies, 7
3. (2) [downloaded on 1 Jan 2018], available at https://ro.uow.edu.au/cgi/viewcontent.cgi?referer=https://www.google.com.hk/&httpsredir=1&article=2088&context=artspapers , pp. 1-14.
4. Foreign Office and the Board of Trade, “Coal Mining Industry in the Hokkaido” dated June 1912 in the Diplomatic and Consular Reports Miscellaneous Series No. 682 (UK: His Majesty’s Stationery Office), 1912, available at
https://digital.soas.ac.uk/content/LO/AC/00/00/66/00168/PDF.pdf
5. Hattori, Ryutaro, “Traditional Folk Songs of Japan Selected and arranged by Ryutaro Hattori from his own collection Part Two: West Japan” dated 1961 (NYC: Folkways Records), 1961, unpaginated [also available online at
https://folkways-media.si.edu/liner_notes/folkways/FW04534.pdf
]