Compare the similar mirror illustrated by Lu Jianguo and Jia Jing in "Some Examples from the Ancient Bronze Mirror Collection of the Baoji Museum," Wenwu, 1991:7, p. 84, fig. 2, where it is dated mid Western Han dynasty. See, also, the similar mirror illustrated by Ju-hsi Chou, Circles of Reflection: The Carter Collection of Chinese Bronze Mirrors, The Cleveland Museum of Art, 2000, p. 34, no. 13, where the author notes that this type of mirror is found in many areas of China at burial sites of mid to late Western Han date.