327 / | HD | MISCELLANEOUS ACTIVE ELECTRICAL NONLINEAR DEVICES, CIRCUITS, AND SYSTEMS |
524 | DF | SPECIFIC IDENTIFIABLE DEVICE, CIRCUIT, OR SYSTEM {22} |
568 | DF | .~ Negative resistance type {4} |
572 | ![]() | .~.~ Secondary emissive type {1} |
573 | DF | .~.~.~> Electron multiplier type |