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Die Rohstoffe unserer Erde : das materielle und geistige Potential der Welt
Guttmann, Henry, (1952)
Energy in the perspective of geography
Guyol, Nathaniel B., (1971)
The geography of economic activity
Thoman, Richard S., (1962)
Resursele hidroenergetice ale globului
Cetină, Elena, (1978)