North Site, Middle Cave, Niche 6-21, right post, 'Douzuyu'
北响堂中洞6－21右侧龛柱“窦祖禹”题名
North Site | Middle Cave
Unknown | Dedicatory Text
Volume 2 Figure 118 in book Xiangtangshan shiku beike tiji zonglu by Zhang Lintang and Xu Peilan
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