Subject Region
United States
32
Soviet Union
15
Europe
7
Developing countries
4
Middle East
3
China
2
Germany
2
Israel
2
Korea
2
Korea (North)
2
Korea (South)
2
American 4 :
1
Caribbean Area
1
European 5 :
1
Germany (East)
1
Germany (West)
1
Great Britain
1
Hiroshima-shi (Japan)
1
Iran
1
Latin America
1
Nagasaki-shi (Japan)
1
Norway
1
Vemork
1