External micrometers / 
British Standards Institution. 
 - 19 pages :  illustrations ;  23cm. 
 - British standard ;  BS 870 : 1950 .
 - British standard ;  BS 870 : 1950 .
<br/><br/><label>Subjects--Topical Terms: </label><br/>Micrometers (Instruments)--Great Britain.<br/>Measuring instruments--Great Britain.