00272nam a2200109Ia 4500008004100000040002500041082002000066100002400086245003500110260000900145300000800154230627s9999    xx            000 0 und d  aNORSU-SiacNORSU-Sia  a622.3340685 B77  aBritton , Scott G.  0aPractical coal mine management  c1981  a233