Linked from
The 9 pages that link to Empress Kōken, each with the reason it gives.
Fujiwara no NakamaroRelated: Her return to power brought Nakamaro’s political rivalry to a head.
Tenpyō-hōjiRelated: Her first reign began before Tenpyō-hōji, and she remained sovereign until 758.
Tenpyō-shōhōRelated: Her first reign began with Tenpyō-shōhō and ended shortly after it.
Tenpyō-kanpōRelated: Her accession followed the brief era during which Shōmu’s reign ended.