| 968 / | HD | HOROLOGY |
| 817 | DD | APPARATUS FOR PRODUCING PRESELECTED TIME INTERVALS FOR USE AS TIMING STANDARDS (generating clock signals for electric digital computers G06F 1/04; regulating frequency in general H03C, L) [G04F 5/00] {6} |
| 822 | | .~ Using oscillators with electromechanical resonators (producing electric oscillations or timing pulses [G04F 5/04] {2} |
| 823 | DD | .~.~> Using piezoelectric resonators [G04F 5/06] {1} |
| 826 | DD | .~.~> Using magnetostrictive resonators [G04F 5/08] |