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. 2021 Mar 23;9:627337. doi: 10.3389/fped.2021.627337

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Copyright © 2021 Zhang, Wang, Zhou, Dong, Zhang, Zhang, Liu, Wu, Yuan, Tang, Dong, Lin, Chen, Tong, Zhao and Yin.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Flow chart of the establishment of the gold standard. Expert group: 2 pediatric pulmonologists with more than 20 years of work experience. Specialist group: 6 pediatric pulmonologists with at least 10 years of work experience.