1.Shandong Ludong Geological Engineering Co., Ltd., Yantai Shandong 264004, China;2.Drilling Engineering Technology Research Center of Shandong Bureau of Geology and Mineral, Yantai Shandong 264004, China;3.Xi’an Northwest Nonferrous Geophysical & Geochemical Exploration Corps Co., Ltd., Xi’an Shannxi 710068, China;4.Shandong No.3 Exploration Institute of Geology and Mineral Resources, Yantai Shandong 264004, China
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