返回Google圖書搜尋

Multiple-shift Mechanical Mining in Some Bituminous Coal Mines

其他書名	Progress report 1
出版	U.S. Department of the Interior, Bureau of Mines, 1938
URL	http://books.google.com.hk/books?id=ZU2TDXFNX3wC&hl=&source=gbs_api
EBook	FULL_PUBLIC_DOMAIN