@book{67606,
	author = {Hoover, Herbert,},
	title = {Principles of Mining: Valuation, Organization and Administration},
	publisher = {Project Gutenberg,},
	year = {2008},
	address = {Salt Lake City, UT :},
	note = {Release date is 2008-09-24},
	url = {https://www.gutenberg.org/ebooks/26697}
}