Stefanko, Robert      frey50        <br/><br/>
Coal mining technology:  Theory and practice / 
Robert Stefanko 
 - New York  Society of Mining Engineers  1983 
 - xiv, 410 p. 
<br/><br/><label>ISBN: </label>0895204045 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Coal mining 
<br/><br/><label>Dewey Class. No.: </label>622.3 Ste   12