"International classification of hard, coals by type" 

 - Geneva  United Nations        1956 
 - 52p.  cm. 
<br/><br/><label>Standard No.: </label>111963 
<br/><br/><label>Source: </label> Reference Collections 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Technology
<br/><br/><label>Dewey Class. No.: </label>"F551:91, J6/UN"