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Subject (Topic)
- DDT (Insecticide)--Environmental aspects79
- Air--Pollution--United States78
- Aquatic biologists--United States78
- Birds--Conservation--United States78
- Conservation of natural resources--United States78
- Ecolog59
- Ecologists--United States21
- Marine biologists--United States21
- Conservation of natural resources --United States3
- Pesticides3
- Pollution --Environmental aspects3
- Fishing--United States2
- Pesticides--Law and legislation2
- Animals.1
- Biological invasions --North America1
- Birds --Conservation --United States1
- Birds--United States1
- Dutch elm disease1
- Gypsy moth.1
- Introduced birds1
