| Year | 1939 |
| Date | 10-Aug |
| Volume | 81 |
| Issue | 1,996 |
| Page | 165 |
| Category | Electrical |
| Part | |
| Title | Building Small Commutators |
| Author | J.Gordon Hall |
| Notes | Showing assembled, showing how cylinder is slit and cut to form segments, segments and mica pressed into 2nd jig ring and conical end grooves |