Transport Museum. (原始内容存档于2008-03-18). Spiral escalator during construction, 1906 Parts of the experimental spiral escalator Ticket hall, 1927 Holloway
[2020-06-25]. (原始内容存档于2020-09-28). McCreesh, Shawn. Protests Near White House Spiral Out of Control Again. The New York Times. June 1, 2020 [June 1, 2020]. (原始内容存档于2020-10-05)
創作的歌曲吸引一般,希望也能透過專輯、透過這些樂曲來吸引更多的聽眾,因此將專輯名稱取為「Gravity」(意指:引力)。同時主打歌「Danger Zone ~to the unknown world~」邀來曾為麥可傑克森、LADY GAGA編舞的Travis Payne負責編排,舞蹈方面更加強烈,企圖打造不同以往的音樂世界。