968 / | HD | HOROLOGY |
103 | DD | MECHANISMS FOR STABILIZING FREQUENCY (magnetic subclass 497; in striking mechanisms subclass 224; stopping and regulating of the running subclass 234; electrical and thermoelectric regulating mechanisms subclass 496) [G04B 17/00] {8} |
107 | DD | .~ Oscillators acting by spring tension [G04B 17/04] {4} |
112 | .~.~ Oscillators with coil springs stretched and unstretched axially [G04B 17/08] |