Communication technology

 
The Links connect with the concerned explanations under  "Hell Development"
   

 
 
 
 
 
 
 
 
year of manufacture
1950  and  1952
 
 
 
 
 
 
 
year of manufacture 1956
 
 
       
 
 
year of manufacture around 1960
 
       
 
 
year of manufacture 1968
 
       
 
 
year of manufacture 1972