361 / | HD | ELECTRICITY: ELECTRICAL SYSTEMS AND DEVICES |
139 | DF | CONTROL CIRCUITS FOR ELECTROMAGNETIC DEVICES {7} |
143 | DF | .~ Systems for magnetizing, demagnetizing, or controlling the magnetic field {5} |
149 | DF | .~.~ Demagnetizing {2} |
150 | ![]() | .~.~.~ Television degaussing |