| Year | 2001 |
| Date | 27-Jul |
| Volume | 187 |
| Issue | 4,151 |
| Page | 65 |
| Category | Correction |
| Part | 3 |
| Title | Gears Without Tears |
| Author | Norman Shaw |
| Notes | Considers pressure angles other than 20deg. Interference, strength of teeth, appearances and scale, cutting 14 1/2deg. teeth, gears to other pressure angles, rack and pinion, serendipity |