лед
52ОКОЛНА СРЕДА- MT
5211природна среда - BT1 вода
- BT2 водна среда
- BT3 природна среда
Mapping
- EXM agrovoc: Agrovoc (FAO - Food and Agriculture Organization)
- EXM gemet: GEMET (GEneral Multilingual Environmental Thesaurus - EEA)
- EXM unbis: Unbis (United Nations Thesaurus)
- EXM unesco: UNESCO (United Nations Educational, Scientific and Cultural Organization)
Bulgarian)