Grant, Ulysses Simpson (2008). Simon, John Y (ed.). The Papers. Vol. 29: 1 October 1878 – 30 September 1880 (illustrated ed.). SIU Press, Ulysses S. Grant Association. p. 165. ISBN978-0-8093-2775-1. Retrieved 11 January 2011.
Akamine, Mamoru (2017). Huey, Robert (ed.). The Ryukyu Kingdom: Cornerstone of East Asia. Translated by Terrell, Lina. Honolulu: University of Hawai'i Press. pp. 5–7. doi:10.2307/j.ctvsrhpp. ISBN9780824855178.
Wade, Geoff (1 July 2007). Ryukyu in the Ming Reign Annals 1380s–1580s (Thesis). Working Paper Series. Asia Research Institute National University of Singapore. p. 75. doi:10.2139/ssrn.1317152. SSRN1317152.
Okinawa Prefectural reserve cultural assets center (2012). "東南アジアと琉球". Comprehensive Database of Archaeological Site Reports in Japan. Retrieved 2 September 2016.
Wade, Geoff (1 July 2007). Ryukyu in the Ming Reign Annals 1380s–1580s (Thesis). Working Paper Series. Asia Research Institute National University of Singapore. p. 75. doi:10.2139/ssrn.1317152. SSRN1317152.