(EN) Section 13 – The Kingdom of the Da Yuezhi 大月氏 (the Kushans), su depts.washington.edu. URL consultato l'11 agosto 2016 (archiviato il 3 marzo 2016).
«Apparently it was Friedrick Hirth in Nachworte zur Inschrift des Tonjukuk: 47-50 who first suggested that xihou represented the Turkish title yabgu.»