subbituminous coal: References & Edit History
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Article Contributors
Primary Contributors
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Otto C. Kopp
Professor Emeritus of Geological Sciences, University of Tennessee, Knoxville.
Other Encyclopedia Britannica Contributors
Article History
| Type | Description | Contributor | Date |
|---|---|---|---|
| Add new Web site: Kentucky Geological Survey - Sub-Bituminous Coal. | Sep 13, 2019 | ||
| Add new Web site: The Balance - Sub-Bituminous Coal Characteristics and Uses. | Sep 13, 2019 | ||
| Add new Web site: U.S. Environment Protection Agency - Bituminous And Subbituminous Coal Combustion. | Jun 22, 2018 | ||
| Updated geologic time data. | Sep 11, 2009 | ||
| Article revised and updated. | Dec 08, 2006 | ||
| Article added to new online database. | Jul 20, 1998 |
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