Block 1 Introduction 

 - Northampton  Open university  1990 
 - 32p.  29cm 
<br/><br/><label>ISBN: </label>0749260432 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Communications engineering
<br/><br/><label>Dewey Class. No.: </label>621.382  / OPE