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Subject
- Geographic Subject: Indiana4
- Topical Subject: Geology3
- Topical Subject: Geology, Stratigraphic3
- Geographic Subject: Illinois2
- Geographic Subject: Michigan2
- Geographic Subject: Calumet Region (Ill. and Ind.)1
- Geographic Subject: Indiana, Northwest1
- Geographic Subject: Lake County (Ind.)1
- Geographic Subject: Ohio1
- Topical Subject: Natural gas pipelines1
- Topical Subject: Petroleum pipelines1
- Topical Subject: Petroleum refineries1