文章特为庆祝北京矿产地质研究院成立50周年而作。

This paper was written for the 50 years anniversary celebration of Beijing Institute of Geology for Mineral Resources.

youdao

文章特为庆祝北京矿产地质研究院成立50周年而作。

This paper was written for the 50 years anniversary celebration of Beijing Institute of Geology for Mineral Resources.

youdao