Geographic Subject
Germany
4
Netherlands
4
Denmark
2
France
2
Sweden
2
5.430
1
6.125
1
Algeria
1
Bavarian Forest
1
Cameroon
1
Costa Rica
1
Developing countries
1
Egypt
1
Germany (West)
1
India
1
Iran
1
Kabalega National Park (Uganda)
1
Korea (South)
1
Medjerda Valley
1
Mexico
1
Neuchâtel (Lake)
1
Nile River Delta
1
Samoa
1
Soviet Union
1
Sudan
1
Switzerland
1
Syria
1
USSR
1