Compare the present lot with a very similar head with a central amphora in the topknot illustrated by Longmen Caves Research Institute in Longmen Liusan Diaoxiang Ji (The Lost Statues of the Longmen Caves), Shanghai, 1993, p. 63, no. 171.
Another Longmen head, with a central Buddha image instead of the amphora and very similar realization of the topknot, in the C. K. Chan Collection, is illustrated in Ancient Chinese Buddhist Sculpture, Taiwan, 1989 no. 9, and again in Fojiao Diaosu Mingpin Tulu (Images of Famous Buddhist Sculpture), Beijing, 1997, p. 330, no. 310.