Among books on yusoku kojitsu, the three books "Saikyuki" written by MINAMOTO no Takaakira, "Hokuzansho" written by FUJIWARA no Kinto, and "Goke-shidai" written by OE no Masafusa were respected as 'kosei no kikan' (a paragon for the future generation) and treated as special cases.
有職故実書の中でも、源高明の『西宮記』、藤原公任の『北山抄』、大江匡房の『江家次第』の三書は「後世の亀鑑」と仰がれ別格扱いであった。