1. https://en.wikipedia.org/wiki/History_of_watches
2. https://museum.seiko.co.jp/knowledge/relation_10/
3. “The use of illuminated girl” The electric world、10.May. 1884、p151 (https://archive.org/details/pub_electrical-world)
4. USP 710429 (1902.10.07) Electric Body Appliance
5. USP 1358509 (1920.11.09) Electric Heating Garment