License, verbatimCC0
The Metropolitan Museum of Art: Open Access, Creative Commons Zero (CC0). Flagged isPublicDomain=true in the museum's own record.
Xuanzong's Preface, Text, and Commentary on the Classic of Filial Piety, also known as Shitai Xiaojing (Stone Platform Classic of Filial Piety). 20th century. The Metropolitan Museum of Art.