Murray, p. 402, p. 402, at Google Books; Hakuhō, also known as Itsunengō; compare Nussbaum, "Hakuhō" at p. 280, p. 280, at Google Books; Hakuhou jidai, JAANUS (Japanese Architecture and Art Net Users System), 2001; retrieved 16 September 2009.
Murray, David. (1894). The Story of Japan, p. 402, p. 402, at Google Books; the system of counting from year-periods (nengō) do not ordinarily overlap with the reigns of the early monarchs; and generally, a new one was chosen whenever it was deemed necessary to commemorate an auspicious or ward off a malign event.
Brown, Delmer M. et al. (1979). Gukanshō, p. 268 n39., p. 268, at Google Books; post-Meiji historians position the reign of Emperor Kōbun between the reigns of Emperor Tenji and Emperor Temmu, but pre-Meiji historians did not construe Prince Ōtomo in the traditional order of succession; compare Ponsonby-Fane, Richard. (1959). The Imperial House of Japan, p. 52; and see Imperial Household Agency (Kunaichō): 天智天皇 (38)
Murray, p. 402, p. 402, at Google Books; Sujaku is also known as an Itsunengō (逸年号)
Murray, p. 402, p. 402, at Google Books; Hakuhō, also known as Itsunengō; compare Nussbaum, "Hakuhō" at p. 280, p. 280, at Google Books; Hakuhou jidai, JAANUS (Japanese Architecture and Art Net Users System), 2001; retrieved 16 September 2009.
Brown, p. 270, p. 270, at Google Books; excerpt, "The eras that fell in this reign were: (1) the remaining seven years of Shuchō [(686+7=692?)]; and (2) Taika, which was four years long [695-698]. (The first year of this era was kinoto-hitsuji [695].) ...In the third year of the Taka era [697], Empress Jitō yielded the throne to the Crown Prince."
Brown, Delmer M. et al. (1979). Gukanshō, p. 268 n39., p. 268, at Google Books; post-Meiji historians position the reign of Emperor Kōbun between the reigns of Emperor Tenji and Emperor Temmu, but pre-Meiji historians did not construe Prince Ōtomo in the traditional order of succession; compare Ponsonby-Fane, Richard. (1959). The Imperial House of Japan, p. 52; and see Imperial Household Agency (Kunaichō): 天智天皇 (38)
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NengoCalc (645) 大化 Taika, online conversion of Japanese dates into their Western equivalents; calculation is based on tables from Tsuchihashi and Zöllner.
Shinengō used prior to the reestablishment of the nengō system in 701 are usually called itsunengō (逸年号). A list of shinengō and more information can be seen in the Japanese Wikipedia page ja:私年号.