1. [1] booklista; Shimirubon, URL: https://shimirubon.jp/, Last Accessed by Nov 27th, 2018.
2. [2] DWANGO; NICO NICO SEIGA, URL: http://seiga.nicovideo.jp/manga/?track=home, Last Accessed by Nov 27th, 2018.
3. [3] Toko-Ai; HONGASUKI, URL: http://www.honzuki.jp/, Last Accessed by Nov 27th, 2018.
4. [4] Amazon; Amazon.co.jp Help: Bookmark, Highlight, Memo, URL: https://www.amazon.co.jp/gp/help/customer/display.html?nodeId=201733790, Last Accessed by Nov 27th, 2018.
5. [5] TRISTA; Dokusyo Meter, URL: https://bookmeter.com/, Last Accessed by Nov 27th, 2018.