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- Geographic Subject: Indiana[remove]438
- Topical Subject: Roads92
- Topical Subject: IGS Annual Reports64
- Topical Subject: Geology49
- Topical Subject: Geology, Stratigraphic43
- Topical Subject: Administrative and political divisions34
- Topical Subject: Mines and mineral resources29
- Topical Subject: Labor supply19
- Topical Subject: SYMAP (Computer program language)18
- Topical Subject: Coal17
- Geographic Subject: Ohio16
- Topical Subject: Coal mines and mining15
- Topical Subject: Railroads15
- Topical Subject: Road materials15
- Geographic Subject: Illinois10
- Geographic Subject: Indianapolis (Ind.)10
- Topical Subject: Central business districts9
- Topical Subject: Oil fields8
- Topical Subject: Gas fields7
- Topical Subject: Population geography7