@book{27387,
	author = {German Society for Soil Mechanics and Foundation Engineering and International Congress on Rock Mechanics (September 16 - 20,1991)},
	title = {Proceedings Seventh International Congress on Rock Mechanics, Zacatecas, Mexico, 16 - 20 1991 : Volume 1 /},
	publisher = {A. A. Balkema,},
	year = {1991},
	address = {Rotterdam :},
	note = {Proceedings 7th Congress on Rock Mechanics, September 16 - 20, 1991  }
}