Cave 171, ceiling <a rel="nofollow" class="external text" href="http://fh.china.com.cn/ch2017/zx/2017-12-26/2283.html">ref</a> <a rel="nofollow" class="external text" href="http://www.360doc.com/content/18/1231/03/49854881_805570410.shtml">ref</a>
Photograph: Nouette Charles (1869-1910) Photographed in 1907. Public Domain
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