| 324 / | HD | ELECTRICITY: MEASURING AND TESTING |
| 323 | DF | OF GEOPHYSICAL SURFACE OR SUBSURFACE IN SITU {7} |
| 347 | DF | .~ Using electrode arrays, circuits, structure, or supports {2} |
| 354 | DF | .~.~ Coupled to artificial current source {2} |
| 357 | DF | .~.~.~ Including separate pickup of generated fields or potentials {6} |
| 366 | DF | .~.~.~.~ For well logging {7} |
| 368 | | .~.~.~.~.~ Cased borehole |