| Year | 1917 |
| Date | 20-Dec |
| Volume | 37 |
| Issue | 869 |
| Page | 384 |
| Category | Electrical |
| Part | 2 |
| Title | Home-made Telephones |
| Author | A.P.Cooper |
| Notes | The exchange, automatic intercommunication, Diagram of connections with a 4-phone circuit, enlarged view of connections at the core, exchange showing connecting wire, conclusion, |