. 2020 Oct 30;8:584964. doi: 10.3389/fpubh.2020.584964
Copyright © 2020 Liu, Ma, Gao, Liu, Liu, Wang, Xie, Wen, Wang, Cheng, Liu, Zou, Wu, Li and Xie.
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Figure 1.
Flow chart of the study design. AGL, above-ground laboratory; DUGL, deep underground laboratory.