African regional conference on telephone signalling systems / 
Org anised by the International Telecommunication Union in Tunis, 8-12, Nov ember, 1971. 
 - Geneva :  [s.n.],  1971. 
 - 201 p. :  tabs., figs., maps ;  29 cm. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Telecommunication.<br/>Telephone.