| Year | 1955 |
| Date | 22-Sep |
| Volume | 113 |
| Issue | 2,835 |
| Page | 399 |
| Category | Expert's Workshop |
| Part | |
| Title | Case Hardening Tools |
| Author | Duplex |
| Notes | The case hardening process. A group of small tools made in the workshop, case-hardened cutters made for motor car repairing |