 |
| low -temperature carbonization: 8 phrases in 3 subjects |
| Natural resourses and wildlife conservation | 1 |
| Oil / petroleum | 5 |
| Technology | 2 |
|
| low -temperature carbonization: 8 phrases in 3 subjects |
| Natural resourses and wildlife conservation | 1 |
| Oil / petroleum | 5 |
| Technology | 2 |