| Year | 1921 |
| Date | 08-Sep |
| Volume | 45 |
| Issue | 1,063 |
| Page | 202 |
| Category | Radio Engineering |
| Part | |
| Title | The Four-Electrode Valve |
| Author | Captain H. de A.Donisthorpe |
| Notes | Rectification circuit, high frequency amplication & rectification circuit, replies to Wireless Enquiries, correct circuit for W.A.K. |