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Subject
- Acid rain--Environmental aspects2
- Administrative and political divisions5
- Agriculture9
- Air quality1
- Air quality management3
- Airports2
- Altitudes3
- American shrew mole1
- Amphibians1
- Animals--Identification2
- Asphalt2
- Atmospheric temperatures2
- Bays3
- Bicycle trails1
- Biodiversity2
- Biodiversity conservation2
- Biogeography34
- Biology and Ecology34
- Biotic communities6
- Birds1