| 505 / | HD | SUPERCONDUCTOR TECHNOLOGY: APPARATUS, MATERIAL, PROCESS |
| 825 | DF | APPARATUS, PER SE, DEVICE, PER SE, OR PROCESS OF MAKING OR OPERATING SAME {36} |
| 888 | DF | .~ Refrigeration: (Class 62) {9} |
| 892 | ![]() | .~.~ Magnetic device cooling {1} |
| 893 | DF | .~.~.~> Spectrometer |