Mitsunobu Tatsumoto R. L. Erickson J.A. Minkin J.M. Back R.V. Buden P.M. Okita Hou Zonglin Meng Qingrun Ren Yingchen Sun Weijun E.H. McKee B. D. Turrin Wang Junwen Li Xibin C.A. Edwards E.C. Chao 1990 application/pdf 10.3133/ofr90538 en U.S. Dept. of the Interior, U.S. Geological Survey, Origin and ages of mineralization of Bayan Obo, the world's largest rare earth ore deposit, Inner Mongolia, China reports