Subject
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Butterflies
1
Camp sites, facilities, etc
1
Canada
1
Canker-worms
1
Caves
3
Celestite
1
Ceratocystis ulmi
1
Chemical analysis
1
Chemical elements
1
Chemicals
1
Chemistry
1
Christmas tree growing
5
Christmas tree industry
1
Christmas trees
7
Chronostratigraphy
1
Classification
2
Clays
1
Clearcutting
1
Cleavage
1
Climate
2
Climatic factors
1
Coal
4
Coal Mines
1
Coal fields
1
Coal industry
1
Coal mines and mining
1
Coal mining
1
Collecting
2
Colluvium
1
Combustion
1
Composition
2
Conifers
1
Conservation
1
Contraception, Immunological
1
Control
4
Copper ores
1
Counties
2
Crown land
1
Crown lands
2
Crystallization
1
DDT (Insecticide)
1
Data processing
2
Deer
2
Depositional history
1
Design and construction
1
Determinative mineralogy
1
Development
1
Devonian
1
Dieback
1
Diseases
1
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