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белый диск (для определения прозрачности воды) | |||
диск Секки |
disk Secchi : 14 phrases in 8 subjects |
Biology | 1 |
Ecology | 1 |
Hydrography | 2 |
Hydrology | 2 |
Information technology | 1 |
Natural resourses and wildlife conservation | 2 |
Nautical | 2 |
Navigation | 3 |