 |
|
time spread : 21 phrases in 13 subjects |
| Air defense | 2 |
| Chemistry | 1 |
| Electronics | 1 |
| Firefighting and fire-control systems | 1 |
| General | 7 |
| Mass media | 1 |
| Mathematics | 1 |
| Non-destructive testing | 1 |
| Polymers | 1 |
| Radiation | 1 |
| Seismology | 1 |
| Technology | 2 |
| Telecommunications | 1 |