Nihon Sandai Jitsuroku

As for the documents and orders mentioned in these writings, I rely on Nihon Sandai Jitsuroku. Nihon Sandai Jitsuroku (literally, The True Record of Three Reigns of Japan) is a history text officially mandated by Emperor Uda to compile. It was compiled by Fujiwara Tokihira, Sugawara Michizane, Okura Yoshiyuki, and Mimune Masahira, and covers the years from August the 27th, 858 to August the 26th, 887 corresponding to three imperial reigns: Seiwa, Yozei, and Koko. The compilation was completed in 901.