柏楊
After Li Chu, whose name had been changed to Li Yu by that point, became emperor in 762 (as Emperor Daizong), Consort Dugu was given the imperial consort rank of "Guifei" (貴妃) in 768—the highest rank among imperial consorts, but not the rank of empress, and it was said that it was for her that Emperor Daizong never made anyone else empress. The modern Chinese historian Bo Yang suggested that the reason was that Emperor Daizong did not want to endanger the position of his oldest son Li Kuo, who was crown prince.)