Ackroyd 1982, p. 298; n.b., shōgun Yoshimasa was succeeded by shōgun Yoshihisa (Yoshimasa's natural son), then by Shogun Yoshitane (Yoshimasa's first adopted son), and then by Shogun Yoshizumi (Yoshimasa's second adopted son) 新井 Arai, 白石 Hakuseki; Ackroyd, Joyce Irene (1982). Lessons from history: the Tokushi yoron. University of Queensland Press. ISBN978-0-7022-1485-1.
Ackroyd 1982, p. 385, n. 104; excerpt, "Some apparent contradictions exist in various versions of the pedigree owing to adoptions and name-changes. Yoshitsuna (sometimes also read Yoshikore) changed his name and was adopted by Yoshitane. Some pedigrees show Yoshitsuna as Yoshizumi's son, and Yoshifuyu as Yoshizumi's son." 新井 Arai, 白石 Hakuseki; Ackroyd, Joyce Irene (1982). Lessons from history: the Tokushi yoron. University of Queensland Press. ISBN978-0-7022-1485-1.
books.google.com
Nussbaum, Louis-Frédéric. (2005). "Muromachi-jidai" in Japan Encyclopedia, p. 669.