 |
| power spectral density: 27 phrases in 13 subjects |
| Astronautics | 3 |
| Electrical engineering | 1 |
| Electronics | 3 |
| Gyroscopes | 1 |
| Household appliances | 1 |
| Mass media | 2 |
| Medical appliances | 1 |
| Metrology | 3 |
| Nautical | 1 |
| Radio | 1 |
| Seismology | 3 |
| Technology | 4 |
| Telecommunications | 3 |