@book{546439,
	author = {Hoek, Evert, and Bawden, W. F.},
	title = {Support of underground excavations in hard rock /},
	publisher = {A.A. Balkema,},
	year = {1997.},
	address = {Rotterdam, Netherlands ;},
	url = {http://www.loc.gov/catdir/enhancements/fy0916/99227305-d.html}
}