Yan Jingshu poses for photo in front of the ancient book restoration center of Zhejiang Library in Hangzhou, east China's Zhejiang Province, May 23, 2018. Yan, 55, has worked in the national level ancient book restoration center of the library for 38 years. She and her colleagues collected more than 200 types of paper to restore ancient books. (Xinhua/Weng Xinyang)